http://braukaiser.com/wiki/api.php?action=feedcontributions&user=Kaiser&feedformat=atomGerman brewing and more - User contributions [en]2024-03-29T07:42:24ZUser contributionsMediaWiki 1.24.1http://braukaiser.com/wiki/index.php?title=Batch_Sparge_and_Party_Gyle_Simulator&diff=5062Batch Sparge and Party Gyle Simulator2018-11-28T02:47:54Z<p>Kaiser: </p>
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The bath sparging process is fairly predictable and can easily be modeled. This is done in the [http://braukaiser.com/documents/batch_sparge_simulator.xls Batch Sparge and Party Gyle simulator], a spread sheet which allows planning of batch sparge and party gyle scenarios. Party Gyle is s style of brewing where the mash is lautered in batches. The resulting worts of different strengths may be blended or not to yield different beers from a single mash. In batch sparge brewing all these run-offs are collected in the same boil kettle to yield a single beer.<br />
<br />
The process is simple. After all or part of the wort has been drained from the lautertun a batch of sparge water is added and mixed well with the grain. The goal is to dilute the wort that remained in the spent grain and distribute its extract evenly throughout the new wort volume. After that the wort is lautered and drained again. This may be repeated one more time but brewers rarely use more than 2 sparge batches which means collecting 3 run-offs.<br />
<br />
The mathematical model simply calculates how much extract is transferred into the boil kettle with reach run-off and how much extract remains in the lautertun before it is diluted by the addition of a known amount of water. The amount of extract that is dissolved during mashing can be calculated from the grist’s extract potential and the [[Understanding_Efficiency#Conversion_efficiency|Conversion Efficiency]] of that mash. It determines the strength of the first wort and to some extend the volume of the first wort. <br />
<br />
The following article explains how to use the spreadsheet.<br />
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=Units=<br />
<br />
[[Image:BSPGS_units.gif|right]]<br />
<br />
While the spreadsheet strictly uses metric units under the hood the user can specify which units should be used for weights, volumes, extract content and grain absorption. It makes sense to save a copy of the spreadsheet loaded with your unit preferences.<br />
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=initial mash=<br />
<br />
[[Image:BSPGS_initial_mash.gif|right]]<br />
<br />
To calculate the amount of extract that will be dissolved the amount of grain, its exract potential (default is 80% fine grind dry basis and 4% moisture content) and the conversion efficiency are needed. The conversion efficiency depends on your mashing parameters and you should get this number from previous mashes. See [[Understanding_Efficiency#Conversion_efficiency|Conversion Efficiency]] on how to measure it. The water amount is needed to calculate the amount of resulting wort and its strength.<br />
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=equipment=<br />
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[[Image:BSPGS_equipment.gif|right]]<br />
<br />
The only equipment parameters that batch sparging depends on are the specific grain absorption and dead spaces. For most brewers dead spaces are virtually nonexistent and commonly found grain absorption is 0.12 gal/lb or 1 l/kg which are the defaults here. If you have better data for your equipment, use it here. Note that the grain absorption and dead space volume is only used to calculate the amount of wort which can be drained. If you don’t rely on that number but enter what you actually collected, these equipment parameters have no effect<br />
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=1st run-off=<br />
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[[Image:BSPGS_1st_run_off.gif|right]]<br />
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Each run-off section gives the volume that can possibly be drained and its strength (gravity). The amount that can be drained is used as the default for the collected volume but can be changed. Based on the collected volume and the wort strength the efficiency collected with that run-off is calculated.<br />
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=boil off options=<br />
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[[Image:BSPGS_boil_off.gif|right]]<br />
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This section is particularly useful to get an idea how strong and how much wort is left after boiling. It lists the post boil volumes and strength for total, not hourly, evaporation percentages ranging from 5 to 30%. In general the evaporation should be between 10 and 15%, which is enough evaporation to drive off DMS and is not yet excessive. But larger beers may need or even benefit from a larger boil-off. The boil-off options are given for each run-off and all of the supported run-off combinations.<br />
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=recharge=<br />
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[[Image:BSPGS_1st_recharge.gif|right]]<br />
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When batch sparging only water is added in preparation of an additional run-off. In party gyle brewing, however, the brewer may decide to add more grain and mash again to boost the gravity of the 2nd run-off.<br />
<br />
This is supported in the recharge sections where the amount of water and grain, which is added, can be entered. Along with the addition of grain is a conversion efficiency number which by default is set to whatever was used in the initial mash section.<br />
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=combined run-offs=<br />
<br />
[[Image:BSPGS_1st_and_2nd_run_off.gif|right]]<br />
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The spreadsheet supports up to 3 run-offs and all combinations with the exception of combining the 1st and the 3rd run-off. In a 2 run-off batch sparge, for example, you would look for the 1st + 2nd run-off section to find your total volume, wort strength and efficiency.<br />
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|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Infusion_Mashing&diff=5061Infusion Mashing2016-05-21T12:33:29Z<p>Kaiser: /* Hochkurz Mash */</p>
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'''Infusion mashing''' is the process of achieving the rest temperatures either by adding measured amounts of water heated to carefully calculated temperatures to the mash or using direct heat to heat the mash.<br />
<br />
In a '''single infusion mash''', the mash water is added all at once and the mash is held at a single steady temperature for the entire mash. In a '''step infusion mash''', some of the water is held back and heated to a carefully calculated temperature before being added to the main mash to raise the temperature to each additional step. In either case, an insulated mash tun, such as a converted picnic cooler mash tun, is used to keep the temperature steady without the need for direct heat. A step infusion mash can also be accomplished with direct heat. <br />
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=Single temperature infusion mash=<br />
<br />
[[Image:Mash_diagram_single_infusion.gif]]<br />
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The single infusion mash uses a single temperature rest at which the beta and alpha amylase enzymes are active to convert the malt starches into wort sugars. The rest temperature controls how long the beta amylase will be active and though that the amount of fermentable sugars that are produced. The higher the mash temperature is, the lower the limit of attenuation of the resulting wort will be. This is the most common mash schedule among home brewers and craft brewers because it is well suited for American and British 2-row malts which are generally highly modified and don't benefit from a lower temperature rests. It is also well suited for the use of unheated mash tuns (e.g. coolers) which are the preferred mash vessel among most home brewers. The rest temperatures are commonly between 149 *F (65 *C) and 165 *F (69 *C). Many brewers like to use 152-154 *F (66.5-67.5*C) as their preferred mash temp as it gives a nice balance of body and fermentability that works well for British and American style ales.<br />
<br />
In order to do a single infusion mash, the strike water (water used for the mash) is heated to a certain temperature such that when the grains are mixed in, the resulting temperature is the desired rest temperature. The temperature of the strike water can be calculated with the following formula [Palmer, 2006]:<br />
<br />
Strike Water Temperature Tw = (.2/R)(T2 - T1) + T2<br />
* R = Ratio of water to grain in quarts per pound<br />
* T1 = the temperature of the grains in Fahrenheit (or Celsius)<br />
* T2 = the target temperature of the mash in Fahrenheit (or Celsius)<br />
<br />
:''Note: Palmer writes that R can be expressed as quarts per pound or liters per kilogram. This is not correct since 1 l/kg is approximately 0.5 qt/lb. This needs to be accounted for when using metric units in the above formula. The temperature however can be used as Fahrenheit or Celsius as long as all temperature values use the same unit or measure.''<br />
<br />
Hitting the mash temperature is for many brewers the biggest problem when doing a single infusion mash. This can some times lead to frustration. The reason for that is, that the above formula doesn't account for heat loss to the mash tun. It basically assumes that the mash tun has a thermal capacity of 0. To get around this one can preheat the mash tun with some boiling water or adjust the strike water temperature based on the results in previous mashes. If the latter is used the brewer should keep the mash tun and grain temperature constant between the different mashes. Another way to eliminate the unknown factor of the mash tun's thermal mass is to adjust the strike water's temperature after it has been added to the mash tun and before the grains are added. This can be done with hot and cold water. <br />
<br />
When mashing in at or above the gelatinization temperature of barley starch (between 140 and 150 *F / 60-65 *C) the grains should be added to the strike water rather than the strike water to the grains. This minimizes the formation of dough balls. Such dough balls form when the starch around them gelatenizes which provides a barrier for mash water. If they are not broken up during dough in, they can later release unconverted starches into the mash.<br />
<br />
With today's highly modified and thus enzymatic strong malts, the mash is generally converted after 15-30 min based on the rest temperature. Lower temperatures mashes convert slower than higher temp mashes of the same grist (see [[The Science of Mashing]] for further details). Most brewers do however mash 60-90 minutes since the fermentability still increases even after the wort itself is iodine negative. In addition to that longer mash times can also increase the conversion efficiency as they convert the harder to reach starch from the malt. It is always a good practice to check for conversion of the mash with a [[Starch Test]]. <br />
<br />
Though this is considered a single temperature step mash, a mash-out rest can be added. Using hot water infusions (or even decoction as shown in [[Decoction Mashing]]) the mash temperature is raised to 167 *F (75 *C). No harm is done if that temperature is not reached exactly. It should however not be exceeded. Many brewers believe that the purpose of this rest is to stop the enzymatic activity, but that is usually not the case as the alpha amylase is not fully deactivated until 176 *F (80 *C). The purpose of the mash-out is to aid lautering as hotter wort will flow more easily while still allowing enzymatic activity to convert any starches that might be unlocked during lautering [Narziss, 2005]. While this is of a lesser concern for the home brewer, a mash-out is still a good practice.<br />
<br />
=Multi step infusion mashes=<br />
<br />
Multi step infusion mashes refer to mashes with more than one temperature rest not counting the mash-out rest. From one step to the next the temperature is generally increased by the use of direct heat, hot water infusions or both. There are various mash rests that can be of interest for the brewer:<br />
* acid rest: for enzymatic mash acidification and no-rush mash pH treatment. Since no significant conversion processes take place at this temperature there is no concern having the mash rest at this temperature for an extended amount of time.<br />
* ferulic acid rest: This is a little different from the regular acid rest as this rest is primarily for the generation of ferulic acid which wheat beer yeasts convert to 4VG, the phenolic character of Bavarian Wheat beers.<br />
* protein rest: This is actually the first additional mash rest that comes to mind when step mashes are discussed. The temperature and extend of this rest depends on the degree of modification of the malt. Rest temperatures closer to 122 *F (50 *F) emphasize the generation of short length proteins (amino acids) and temperatures closer to 133 *F (55 *C) result in more medium chained proteins (good for head retention and body). Well modified modern malts, which already have higher levels of amino acids, may benefit from a protein rest closer to 133*F (55 *C) or don't require a protein rest at all. <br />
* saccharification rest: This can be done as a single saccharification rest like it is used for single infusion mashes or multiple rests which emphasize beta and alpha amylase separately. The latter can result in better fermentability of the wort since it gets the most out of the beta amylase and limit dextrinase which are the main producers of fermentable sugars.<br />
<br />
When direct heat is used to increase the mash temperature between the rests, the temperature should only rise 2-4 *F (1-2 *C) per minute. Going faster may risk scorching of the mash.<br />
<br />
The following is an example of a 2 step infusion mash that works well with moderately well modified German malts:<br />
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[[Image:Mash_diagram_2_step_infusion.gif]]<br />
<br />
It employs a short protein rest at 133 *F (55*C) and a single saccharification rest. The temperature is increased by the use of boiling water. To run as mash schedule like this, calculate the strike water temperature for your grain, a grist/water ratio of 1.25 qts/lb (~2.5 L/kg) and a rest temperature of 129-133 *F (53-55 *F). Add the water to the grain. Since the dough in happens below the gelatinization temperature of barley starch it is safe to add the water to the grain since there won't be any dough balls. There is also nothing wrong with adding the grain to the water, but it might be convenient to mill the grain directly into the mash tun. The temperature should stabilize somewhere between 122 and 133 *F (50-55 *C). If it is too close to 50, don't worry, just shorten the length of the protein rest or add some boiling water to raise the mash temp closer to 55*F. This assumes that you use fairly well modified (not overmodified) modern lager malts. Use this rest to measure and adjust the pH of the mash if you are set up to do that. The later addition of more water will not have any significant effect on this pH. While the mash is resting at the protein rest bring about 60-70% of the amount of water that you used as strike water to a boil. When the protein rest is over use a heat resistant vessel to scoop some boiling water into the mash and stir to mix it well. Measure the temperature and repeat the process until you hit the desired saccharification rest temp. This rest temp will depend on the desired attenuation of the wort and you will have to find the optimal temperature by experimenting. As a start you can use the temp that you would use for a single infusion mash. But due to the protein rest and limited beta amylase and limit dextrinase activity during that rest, the resulting wort fermentability will be higher compared to a single infusion mash at the same saccharification rest temperature.<br />
<br />
You could also use this formula to calculate the amount of water that needs to be added to raise the mash temperature [Palmer, 2006]:<br />
<br />
Wa = (T2 - T1)(0.2G + Wm)/(Tw - T2)<br />
<br />
*Wa = The amount of infusion water added<br />
*Wm = The total amount of water in the mash<br />
*T1 = The initial mash temperature<br />
*T2 = The target mash temperature<br />
*Tw = the actual temperature of the infusion water<br />
*G = The amount of grain in the mash<br />
<br />
But the addition of boiling water until the new rest temp is reached is more reliable as it can account for factors that the above formula can't. And since the resulting mash will be quite thin, stirring it and getting the heat evenly distributed for a reliable mash temp reading is not as difficult as it is in a ticker single infusion mash.<br />
<br />
Some brewers are concerned that a thinner mash leads to more tannin extraction, but quite the opposite is true. German brewers prefer thinner mashes for delicate and lighter colored beers as it will produce more of the desirable first wort and since less sparge water needs to be used less tannins are extracted during lautering.<br />
<br />
The enzymatic activity also benefits from the changing mash thickness. A thicker mash during the protein rest enhances the protoelytic activity and a thinner mash during the saccharification rest enhances the amylase activity.<br />
<br />
If there is room left in the mash tun, mash-out can also be reached though another infusion with boiling water or through a decoction. The latter is covered in [[Decoction Mashing]].<br />
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=Hochkurz Mash=<br />
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[[Image:Mash_diagram_infusion_hochkurz.gif]]<br />
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Another stepped infusion mash that I want to highlight here is the Hochkurz mash. There is also a decoction version of this mash which is described in the [[Decoction Mashing]] article. Here we want to focus on the infusion version of this mash schedule. Hochkurz is the combination of 2 German words: ''hoch'' means high and ''kurz'' means short. It refers to the fact that the mash doughs in at a high temperature (above protein rest temperatures) and is fairly short (less than 2 hours).<br />
<br />
The Hochkurz mash has become the standard mashing schedule for beers brewed in Germany. Especially large breweries like it because it doesn’t require decoction and can be done in less than 2 hours which fits well with their desire to be able to mash a new batch every 2 hours. It uses 2 different sacharification rests; one for each group of amylase enzymes. A low temperature rest favors the beta amylase and sets the fermentbility of the wort. A high temperature rest favors the alpha amylase and completes the starch conversion. <br />
<br />
The temperature steps necessary for this mash schedule can be achieved through infusions of boiling water or direct heat. If boiling water will be used the mash should be doughed in with a water to grist ratio of about 2.5 – 3 l/kg (1.25 – 1.5 qt/lb). Don’t be afraid of thinning out the mash through the hot water infusions. It will become easier to handle and enzymes and gelatinization also work better in a thinner mash. <br />
<br />
If direct heat is used aim for a mash thickness of 3.5 – 4.5 l/kg (1.75 – 2.25 qt/lb). This is the mash thickness that is commonly used in Germany and it makes stirring the mash during the heating phases much easier. You should also aim for a dough-in temperature that is slightly lower than the first rest temperature since it is much easier ho heat the mash than to cool it in case the first rest temperature is not hit after dough-in.<br />
<br />
The first rest (maltose rest) should be held at or around 63C (145F) and it’s length is used to control the fermentability of the wort. A good starting point for its duration is 30 min. Longer for more fermentable wort and shorter for less fermentable wort. If even higher fermentability is desired an intermediate rest at 65C (150F) can be added. Due to its large volume the mash temperature should not drop much during that rest but you may wrap the pot into blankets to stabilize the mash temp even more.<br />
<br />
The dextrinization rest at 70-72C (158-162F) needs to be held until the mash is iodine negative but may be extended to 45-60 min. Many authors contribute head retention and mouthfeel benefits to extending this rest. Finally the mash may be raised to mash out temp and subsequently lautered.<br />
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|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5060PWM Coltrolled Stir Plate Design2013-07-01T01:11:40Z<p>Kaiser: /* part list */</p>
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=Introduction=<br />
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A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
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=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
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=PWM design=<br />
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[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
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{| class="wikitable" <br />
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! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| Q1 || MOSFET NFET DPAK 30V 54A 5.5 mOhm || 863-NTD4906N-35G <br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
[[File:StirPlatePWM-1.jpg|frame|center|Picture of the completed double stir plate. This design is 14 inches wide, 7 inches deep and 2.5 inches high. ]]<br />
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[[File:StirPlatePWM-2.jpg|frame|center]]<br />
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==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this circuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.<br />
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|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM_wiring.gif&diff=5059File:StirPlatePWM wiring.gif2013-07-01T01:09:57Z<p>Kaiser: Kaiser uploaded a new version of &quot;File:StirPlatePWM wiring.gif&quot;</p>
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<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Braukaiser.com&diff=5058Braukaiser.com2013-05-08T22:22:23Z<p>Kaiser: /* What’s New */</p>
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[[Image:Braukaiser_header.jpg]]<br />
<br />
Welcome to Braukaiser.com. This site is dedicated to brewing science and topics that are mostly related to brewing German style beers and it is not intended to be a complete reference for the home brewing process. It is a rather loose collection of various articles.<br />
<br />
'''Philosophy'''<br />
<br />
I enjoy the scientific and technological aspects brewing, which shows in the articles, and want to promote a better understanding of them as well as introduce the advanced brewer to various brewing techniques. Being an engineer I like to know what is happening and how I can control the final product and fix problems when they arise. Despite what many readers would think, I'm a fairly relaxed brewer. Some of that relaxation comes from knowing the process and knowing where attention is necessary and where not.<br />
<br />
For questions and suggestions contact '''kai at braukaiser dot com'''<br />
<br />
<br />
'''Blogs'''<br />
<br />
There are also two blogs that I'm maintaining<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Blog_general.jpg|link=http://braukaiser.com/blog/]] <br />
| [[Image:Blog_beers.jpg|link=http://braukaiser.com/blog/beers]]<br />
|-<br />
| [http://braukaiser.com/blog/ '''Braukaiser.com - Blog'''] is a convenient place to report about experiments and ramble about random subjects <br />
| [http://braukaiser.com/blog/beers/ '''Commercial Beer Reviews'''] started as a tasting report of almost 80 different beers that I had on a trip to Germany<br />
|-<br />
| 10-9-12 [http://braukaiser.com/blog/blog/2012/10/08/yeast-growth-experiments-some-early-results/ Yeast growth experiments - some early results]<br />
<br />
10-03-12 [http://braukaiser.com/blog/blog/2012/10/03/yeast-un-flocculation-for-cell-counting/ Yeas un-flocculation for cell counting]<br />
<br />
09-16-12 [http://braukaiser.com/blog/blog/2012/09/16/enzymes-in-the-fermenter/ Enzymes in the fermenter]<br />
<br />
09-09-12 [http://braukaiser.com/blog/blog/2012/09/09/hops-from-a-can/ Hops From A Can]<br />
| <br />
|}<br />
<br />
<br />
<br />
<br />
'''Icons'''<br />
<br />
More recent articles on this site use symbols on the right margins to indicate the type of content and allow readers to skip possibly uninteresting or complex part<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Icon_basics.gif|link=|alt={Brewing Basics}]]<br />
|'''Brewing Basics:''' The building blocks stand for basic stuff that is important for the understanding of further discussions and elaborations.<br />
|- <br />
| valign="top" | [[Image:Icon_inner_workings.gif|link=|alt={How Things Work}]]<br />
|'''How Things Work:''' the cogs mark sections that detail how a particular process woks<br />
|-<br />
| valign="top" | [[Image:Icon_brewing_advice.gif|link=|alt={Practical Brewing Advice}]]<br />
|'''Practical Brewing Advice:''' The pot stands for practical brewing advice that will help you in home brewing. Oftentimes a conclusion that is drawn from preceding, more complex, content.<br />
|-<br />
| valign="top" | [[Image:Icon_science.gif|link=|alt={Geeky Stuff}]]<br />
|'''Geeky Stuff:''' The test tube stands for geeky content. Something that is cool to know but has only little importance in practical home brewing.<br />
|}<br />
<br />
<br />
=What’s New=<br />
<br />
* '''May 2013''' - added [[PWM stir plate design]]<br />
* '''Mar 2013''' - added [[Lactate Taste Threshold experiment]]<br />
* '''Oct 2012''' - added [[Microscope use in brewing]]<br />
* '''Apr 2012''' - added [[Yeast Propagator]]<br />
* '''Mar 2012''' - added [[Beer color to mash pH (v2.0)]]<br />
* '''Jul 2011''' - fixed the images that got lost after some post-hacking clean-up<br />
* '''Feb 2011''' - added [[Mash pH control]]<br />
* '''Feb 2011''' - added [[Iodine Test]]<br />
* '''Jan 2011''' - added [[A simple Model for pH Buffers]]<br />
* '''Jun 2010''' - published [http://braukaiser.com/download/Troester_NHC_2010_Efficiency.pdf NHC 2010 presentation about efficiency and how to keep it predictable]<br />
* '''Jun 2010''' - added documentation for the [[Batch Sparge and Party Gyle Simulator]]<br />
* '''May 2010''' - added [[How to read a water report]]<br />
* '''Mar 2010''' - released [[Alkalinity reduction with slaked lime]]<br />
* '''Feb 2010''' - released [[Beer color, alkalinity and mash pH]]<br />
* '''Jan 2010''' - added [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
= Preparation =<br />
* [[Keeping Log]]<br />
* [[Carboy Washer]]<br />
<br />
= (Brewing) Science Basics =<br />
<br />
* Everything you need to know about pH in brewing<br />
** '''pH part 1''': [[An Overview of pH]]<br />
*** [[A simple Model for pH Buffers]]<br />
*** [[pH Meter Buying Guide]]<br />
*** [[An Evaluation of the suitability of colorpHast strips for pH measurements in home brewing]]<br />
** '''pH part 2''': [[How pH affects brewing]]<br />
** '''pH part 3''': [[Mash pH control]]<br />
*** [[Residual Alkalinity illustrated]]<br />
** [[Beer color, alkalinity and mash pH]]<br />
** [[Beer color to mash pH (v2.0)]]<br />
* [http://braukaiser.com/documents/effect_of_water_and_grist_on_mash_pH.pdf Effect of water and grist on mash pH (paper)]<br />
* [[Lactate Taste Threshold experiment]]<br />
<br />
=Ingedients=<br />
<br />
* Water<br />
** [[How to read a water report]]<br />
** [[At home water testing]]<br />
** [[Building brewing water with dissolved chalk]]<br />
** [[Alkalinity reduction with lime]]<br />
** [http://braukaiser.com/documents/Kaiser_water_calculator.xls Kaiser_water_calculator.xls] | [http://braukaiser.com/documents/Kaiser_water_calculator_US_units.xls Kaiser_water_calculator_US_units.xls]<br />
<br />
= Wort Production =<br />
<br />
* [[CrushEval|Evaluating the Crush of the Grain]]<br />
* [[Malt Conditioning]]<br />
* [[The Science of Mashing]]<br />
** [[Enzymes]]<br />
** [[Carbohydrates]]<br />
** [[Starch Conversion]]<br />
* [[The Theory of Mashing]] - revised and largely replaced by [[The Science of Mashing]]<br />
** Experiment: [[Mash Time Dependency of Wort Fermentability]]<br />
** Experiment: [[Effects of mash parameters on fermentability and efficiency in single infusion mashing]]<br />
* [[Infusion Mashing]]<br />
* [[Decoction Mashing]]<br />
* [[Batch Sparging Analysis]]<br />
* [[Iodine Test]]<br />
* [[Understanding Efficiency]]<br />
* [[Troubleshooting Brewhouse Efficiency]]<br />
* [[Batch Sparge and Party Gyle Simulator]]<br />
<br />
= Boiling and Wort Transfer =<br />
<br />
* [[Whirlpooling]]<br />
<br />
= Fermentation =<br />
* [[Understanding Attenuation]]<br />
* [[Fast Ferment Test]]<br />
* [[Fermenting Lagers]]<br />
* [[Drauflassen]]<br />
* [[Carbonation Tables]]<br />
* [[Kraeusening]]<br />
* [[Accurately Calculating Sugar Additions for Carbonation]]<br />
* '''Yeast Culturing'''<br />
** [[Yeast culturing gear]]<br />
** [[Making Plates and Slants]]<br />
** [[Inoculating Plates and Slants]]<br />
** [[Growing Yeast from a Plate]]<br />
** [[Yeast Propagator]]<br />
** [[Yeast Bank contents]]<br />
** [[Microscope use in brewing]]<br />
** [[PWM stir plate design]]<br />
* '''Experiments'''<br />
** [[Experiment Pitching Rate and Oxygenation|Pitching Rate and Oxygenation]]<br />
<br />
=Bottling/Kegging/Serving=<br />
<br />
* [[Kompensatorzapfhahn]]<br />
<br />
= Breweries =<br />
===Germany===<br />
* [[Museums- und Traditionsbrauerei Wippra|Museums- und Traditionsbrauerei Wippra (museum and traditonal brewery Wippra), Germany]]<br />
* [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
===History===<br />
* German Brewing between 1850 and 1900<br />
** Part I: [[German Brewing between 1850 and 1900 : Malting and Wort Production|Malting and Wort Production]]<br />
** Part II: [[German Brewing between 1850 and 1900: Fermentation and Beer|Fermentation and Beer]]<br />
<br />
= Literature =<br />
<br />
= Misc =<br />
* [[Links]]<br />
* [[Recipes]]<br />
** [[Various water recipes]]<br />
** Obergäriges (Ales)<br />
*** [[Kaiser Alt]]<br />
*** [[Weissbier Hell]]<br />
** Untergäriges (Lagers)<br />
*** [[Dunkel]]<br />
*** [[Schwarzbier]]<br />
*** [[Maibock]]<br />
*** [[Imperator|Imperator (Doppelbock)]]<br />
*** [[Edel Hell]]<br />
** Food<br />
*** [[Treberbrot]]<br />
*** [[Brezels and other Laugengebäck]]<br />
* [[Glossary of German Brewing Terms]]<br />
* [[Tables for Conversions and Calculations]]<br />
* [[Foreign Content]]<br />
* [[Podcasts]]<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Braukaiser.com&diff=5057Braukaiser.com2013-05-08T22:22:04Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
[[Image:Braukaiser_header.jpg]]<br />
<br />
Welcome to Braukaiser.com. This site is dedicated to brewing science and topics that are mostly related to brewing German style beers and it is not intended to be a complete reference for the home brewing process. It is a rather loose collection of various articles.<br />
<br />
'''Philosophy'''<br />
<br />
I enjoy the scientific and technological aspects brewing, which shows in the articles, and want to promote a better understanding of them as well as introduce the advanced brewer to various brewing techniques. Being an engineer I like to know what is happening and how I can control the final product and fix problems when they arise. Despite what many readers would think, I'm a fairly relaxed brewer. Some of that relaxation comes from knowing the process and knowing where attention is necessary and where not.<br />
<br />
For questions and suggestions contact '''kai at braukaiser dot com'''<br />
<br />
<br />
'''Blogs'''<br />
<br />
There are also two blogs that I'm maintaining<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Blog_general.jpg|link=http://braukaiser.com/blog/]] <br />
| [[Image:Blog_beers.jpg|link=http://braukaiser.com/blog/beers]]<br />
|-<br />
| [http://braukaiser.com/blog/ '''Braukaiser.com - Blog'''] is a convenient place to report about experiments and ramble about random subjects <br />
| [http://braukaiser.com/blog/beers/ '''Commercial Beer Reviews'''] started as a tasting report of almost 80 different beers that I had on a trip to Germany<br />
|-<br />
| 10-9-12 [http://braukaiser.com/blog/blog/2012/10/08/yeast-growth-experiments-some-early-results/ Yeast growth experiments - some early results]<br />
<br />
10-03-12 [http://braukaiser.com/blog/blog/2012/10/03/yeast-un-flocculation-for-cell-counting/ Yeas un-flocculation for cell counting]<br />
<br />
09-16-12 [http://braukaiser.com/blog/blog/2012/09/16/enzymes-in-the-fermenter/ Enzymes in the fermenter]<br />
<br />
09-09-12 [http://braukaiser.com/blog/blog/2012/09/09/hops-from-a-can/ Hops From A Can]<br />
| <br />
|}<br />
<br />
<br />
<br />
<br />
'''Icons'''<br />
<br />
More recent articles on this site use symbols on the right margins to indicate the type of content and allow readers to skip possibly uninteresting or complex part<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Icon_basics.gif|link=|alt={Brewing Basics}]]<br />
|'''Brewing Basics:''' The building blocks stand for basic stuff that is important for the understanding of further discussions and elaborations.<br />
|- <br />
| valign="top" | [[Image:Icon_inner_workings.gif|link=|alt={How Things Work}]]<br />
|'''How Things Work:''' the cogs mark sections that detail how a particular process woks<br />
|-<br />
| valign="top" | [[Image:Icon_brewing_advice.gif|link=|alt={Practical Brewing Advice}]]<br />
|'''Practical Brewing Advice:''' The pot stands for practical brewing advice that will help you in home brewing. Oftentimes a conclusion that is drawn from preceding, more complex, content.<br />
|-<br />
| valign="top" | [[Image:Icon_science.gif|link=|alt={Geeky Stuff}]]<br />
|'''Geeky Stuff:''' The test tube stands for geeky content. Something that is cool to know but has only little importance in practical home brewing.<br />
|}<br />
<br />
<br />
=What’s New=<br />
<br />
* '''May 2013''' - added [PWM stir plate design]]<br />
* '''Mar 2013''' - added [[Lactate Taste Threshold experiment]]<br />
* '''Oct 2012''' - added [[Microscope use in brewing]]<br />
* '''Apr 2012''' - added [[Yeast Propagator]]<br />
* '''Mar 2012''' - added [[Beer color to mash pH (v2.0)]]<br />
* '''Jul 2011''' - fixed the images that got lost after some post-hacking clean-up<br />
* '''Feb 2011''' - added [[Mash pH control]]<br />
* '''Feb 2011''' - added [[Iodine Test]]<br />
* '''Jan 2011''' - added [[A simple Model for pH Buffers]]<br />
* '''Jun 2010''' - published [http://braukaiser.com/download/Troester_NHC_2010_Efficiency.pdf NHC 2010 presentation about efficiency and how to keep it predictable]<br />
* '''Jun 2010''' - added documentation for the [[Batch Sparge and Party Gyle Simulator]]<br />
* '''May 2010''' - added [[How to read a water report]]<br />
* '''Mar 2010''' - released [[Alkalinity reduction with slaked lime]]<br />
* '''Feb 2010''' - released [[Beer color, alkalinity and mash pH]]<br />
* '''Jan 2010''' - added [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
= Preparation =<br />
* [[Keeping Log]]<br />
* [[Carboy Washer]]<br />
<br />
= (Brewing) Science Basics =<br />
<br />
* Everything you need to know about pH in brewing<br />
** '''pH part 1''': [[An Overview of pH]]<br />
*** [[A simple Model for pH Buffers]]<br />
*** [[pH Meter Buying Guide]]<br />
*** [[An Evaluation of the suitability of colorpHast strips for pH measurements in home brewing]]<br />
** '''pH part 2''': [[How pH affects brewing]]<br />
** '''pH part 3''': [[Mash pH control]]<br />
*** [[Residual Alkalinity illustrated]]<br />
** [[Beer color, alkalinity and mash pH]]<br />
** [[Beer color to mash pH (v2.0)]]<br />
* [http://braukaiser.com/documents/effect_of_water_and_grist_on_mash_pH.pdf Effect of water and grist on mash pH (paper)]<br />
* [[Lactate Taste Threshold experiment]]<br />
<br />
=Ingedients=<br />
<br />
* Water<br />
** [[How to read a water report]]<br />
** [[At home water testing]]<br />
** [[Building brewing water with dissolved chalk]]<br />
** [[Alkalinity reduction with lime]]<br />
** [http://braukaiser.com/documents/Kaiser_water_calculator.xls Kaiser_water_calculator.xls] | [http://braukaiser.com/documents/Kaiser_water_calculator_US_units.xls Kaiser_water_calculator_US_units.xls]<br />
<br />
= Wort Production =<br />
<br />
* [[CrushEval|Evaluating the Crush of the Grain]]<br />
* [[Malt Conditioning]]<br />
* [[The Science of Mashing]]<br />
** [[Enzymes]]<br />
** [[Carbohydrates]]<br />
** [[Starch Conversion]]<br />
* [[The Theory of Mashing]] - revised and largely replaced by [[The Science of Mashing]]<br />
** Experiment: [[Mash Time Dependency of Wort Fermentability]]<br />
** Experiment: [[Effects of mash parameters on fermentability and efficiency in single infusion mashing]]<br />
* [[Infusion Mashing]]<br />
* [[Decoction Mashing]]<br />
* [[Batch Sparging Analysis]]<br />
* [[Iodine Test]]<br />
* [[Understanding Efficiency]]<br />
* [[Troubleshooting Brewhouse Efficiency]]<br />
* [[Batch Sparge and Party Gyle Simulator]]<br />
<br />
= Boiling and Wort Transfer =<br />
<br />
* [[Whirlpooling]]<br />
<br />
= Fermentation =<br />
* [[Understanding Attenuation]]<br />
* [[Fast Ferment Test]]<br />
* [[Fermenting Lagers]]<br />
* [[Drauflassen]]<br />
* [[Carbonation Tables]]<br />
* [[Kraeusening]]<br />
* [[Accurately Calculating Sugar Additions for Carbonation]]<br />
* '''Yeast Culturing'''<br />
** [[Yeast culturing gear]]<br />
** [[Making Plates and Slants]]<br />
** [[Inoculating Plates and Slants]]<br />
** [[Growing Yeast from a Plate]]<br />
** [[Yeast Propagator]]<br />
** [[Yeast Bank contents]]<br />
** [[Microscope use in brewing]]<br />
** [[PWM stir plate design]]<br />
* '''Experiments'''<br />
** [[Experiment Pitching Rate and Oxygenation|Pitching Rate and Oxygenation]]<br />
<br />
=Bottling/Kegging/Serving=<br />
<br />
* [[Kompensatorzapfhahn]]<br />
<br />
= Breweries =<br />
===Germany===<br />
* [[Museums- und Traditionsbrauerei Wippra|Museums- und Traditionsbrauerei Wippra (museum and traditonal brewery Wippra), Germany]]<br />
* [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
===History===<br />
* German Brewing between 1850 and 1900<br />
** Part I: [[German Brewing between 1850 and 1900 : Malting and Wort Production|Malting and Wort Production]]<br />
** Part II: [[German Brewing between 1850 and 1900: Fermentation and Beer|Fermentation and Beer]]<br />
<br />
= Literature =<br />
<br />
= Misc =<br />
* [[Links]]<br />
* [[Recipes]]<br />
** [[Various water recipes]]<br />
** Obergäriges (Ales)<br />
*** [[Kaiser Alt]]<br />
*** [[Weissbier Hell]]<br />
** Untergäriges (Lagers)<br />
*** [[Dunkel]]<br />
*** [[Schwarzbier]]<br />
*** [[Maibock]]<br />
*** [[Imperator|Imperator (Doppelbock)]]<br />
*** [[Edel Hell]]<br />
** Food<br />
*** [[Treberbrot]]<br />
*** [[Brezels and other Laugengebäck]]<br />
* [[Glossary of German Brewing Terms]]<br />
* [[Tables for Conversions and Calculations]]<br />
* [[Foreign Content]]<br />
* [[Podcasts]]<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5056PWM Coltrolled Stir Plate Design2013-05-08T22:20:53Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
[[File:StirPlatePWM-1.jpg|frame|center|Picture of the completed double stir plate. This design is 14 inches wide, 7 inches deep and 2.5 inches high. ]]<br />
<br />
[[File:StirPlatePWM-2.jpg|frame|center]]<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this circuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5055PWM Coltrolled Stir Plate Design2013-05-08T22:20:35Z<p>Kaiser: /* Housing */</p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
[[File:StirPlatePWM-1.jpg|frame|center|Picture of the completed double stir plate. This design is 14 inches wide, 7 inches deep and 2.5 inches high. ]]<br />
<br />
[[File:StirPlatePWM-2.jpg|frame|center]]<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this circuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM-1.jpg&diff=5054File:StirPlatePWM-1.jpg2013-05-08T00:36:30Z<p>Kaiser: Kaiser uploaded a new version of &quot;File:StirPlatePWM-1.jpg&quot;</p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5053PWM Coltrolled Stir Plate Design2013-05-07T21:34:34Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
[[File:StirPlatePWM-1.jpg|frame|center]]<br />
<br />
[[File:StirPlatePWM-2.jpg|frame|center]]<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this circuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5052PWM Coltrolled Stir Plate Design2013-05-07T21:33:31Z<p>Kaiser: /* Housing */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
[[File:StirPlatePWM-1.jpg|frame|center]]<br />
<br />
[[File:StirPlatePWM-2.jpg|frame|center]]<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM-2.jpg&diff=5051File:StirPlatePWM-2.jpg2013-05-07T21:32:37Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM-1.jpg&diff=5050File:StirPlatePWM-1.jpg2013-05-07T21:32:16Z<p>Kaiser: Kaiser uploaded a new version of &quot;File:StirPlatePWM-1.jpg&quot;</p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM-1.jpg&diff=5049File:StirPlatePWM-1.jpg2013-05-07T21:31:01Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5048PWM Coltrolled Stir Plate Design2013-05-07T21:26:32Z<p>Kaiser: /* part list */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5047PWM Coltrolled Stir Plate Design2013-05-07T21:26:14Z<p>Kaiser: /* part list */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including [http://mouser.com mouser.com] item numbers. The part numbers are given for reference and no guarantee is made for their correctness.<br />
<br />
{| class="wikitable" <br />
|- <br />
! id !! description !! mouser.com model item number !!<br />
|- <br />
| 555 || NE555N timer chip || 511-NE555N ||<br />
|- <br />
| D1, D2, D3 || general purpose diode || 625-1N4933-E3<br />
|- <br />
| C1 || Aluminum Electrolytic Capacitors, 2.2 uF || 647-UVY2A2R2MDD<br />
|- <br />
| P1 || 100k linear potentiometer || 858-P160KNP0C20B100K NOTE: I was not able to find a good knob for this potentiometer. <br />
|- <br />
| C2 || Aluminum Electrolytic Capacitors, 22 uF || 140-RGA220M2ABK0811G<br />
|- <br />
| C3 || Multilayer Ceramic Capacitor, 0.1 uF || 810-FK18X7R1E104K<br />
|-<br />
| M || 12 V DC fan || 670-OD8025-12HSS<br />
|} <br />
<br />
You'll also need a 12V DC power supply and a jack for connecting this power supply.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5046PWM Coltrolled Stir Plate Design2013-05-07T21:12:28Z<p>Kaiser: /* part list */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers.<br />
<br />
{<br />
|| id || description || mouser.com model item number ||<br />
<br />
}<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5045PWM Coltrolled Stir Plate Design2013-05-07T21:03:57Z<p>Kaiser: /* Wiring diagram and parts list */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
[[File:StirPlatePWM breadboard.gif|frame|center|Figure 4 - suggested breadboard layout]]<br />
<br />
Figure 4 shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits which is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM_breadboard.gif&diff=5044File:StirPlatePWM breadboard.gif2013-05-07T21:02:27Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5043PWM Coltrolled Stir Plate Design2013-05-07T20:58:06Z<p>Kaiser: /* Wiring diagram and parts list */</p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
[[File:StirPlatePWM wiring.gif|frame|center|Figure 3 - Wiring diagram of the PWM control logic and the DC fan]]<br />
<br />
Figure 3 shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control which section of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that protects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers.<br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:StirPlatePWM_wiring.gif&diff=5042File:StirPlatePWM wiring.gif2013-05-07T20:55:50Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5041PWM Coltrolled Stir Plate Design2013-05-07T03:20:12Z<p>Kaiser: </p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|center|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5040PWM Coltrolled Stir Plate Design2013-05-07T03:19:57Z<p>Kaiser: </p>
<hr />
<div>[[File:Work_in_progress.jpg]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|right|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5039PWM Coltrolled Stir Plate Design2013-05-07T03:18:03Z<p>Kaiser: </p>
<hr />
<div>[[File:Work_in_progress.gif]]<br />
<br />
=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
[[File:PWM detail.gif|frame|right|Figure 2 - Charging and discharging the capacitor causes the generation of pulses on the Q output. The width of these pulses depend on R1 and R2 which are based the current position of the potentiometer]]<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:PWM_detail.gif&diff=5038File:PWM detail.gif2013-05-07T03:14:39Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5037PWM Coltrolled Stir Plate Design2013-05-07T03:14:12Z<p>Kaiser: </p>
<hr />
<div>=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. Changing the capacitance of a capacitor is difficult but changing the resistance of a resistor is much easier, which why the capacitance remains constant but the resistance is changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable paths of a potentiometer and diodes. Figure 2 illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
<br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5036PWM Coltrolled Stir Plate Design2013-05-07T03:05:41Z<p>Kaiser: </p>
<hr />
<div>=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
[[File:555 internals.gif|frame|right|Figure 1 - the internals of the NE555N timer chip connected to a capacitor that can be charged and discharged through a variable resistor]]<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. In this design the capacitance remains constant but the resistance can be changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable resistors and diodes. Figure ?? illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=File:555_internals.gif&diff=5035File:555 internals.gif2013-05-07T03:03:45Z<p>Kaiser: </p>
<hr />
<div></div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5034PWM Coltrolled Stir Plate Design2013-05-07T02:57:41Z<p>Kaiser: </p>
<hr />
<div>=Introduction=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitized. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers, including my own, have shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or acquiring stir plates. Given the fairly high price ($50 for a simple design and $100+ for most commercial models) many home brewers op for building their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitated but have the capacity to hold many flasks at once. Building a shaker table is more complicated than a stir plate which is why they are not commonly used by home brewers.<br />
<br />
=Design options=<br />
<br />
Most home built stir plates use a DC fan to which strong magnets are attached. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan speed through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control problem is overcome by pulse width modulation (PMW), which does not change the voltage applied to the fan but the amount of time the fan is turned on and off. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
=PWM design=<br />
<br />
The fan speed control logic described here is based on a [http://www.homebrewtalk.com/f51/simple-pwm-stirplate-controller-219121/ Home Brew Talk post] by rocketman768 with a few modifications. It employs a [http://www.mouser.com/ds/2/389/CD00000479-103226.pdf NE555N] timer chip. The internals of the NE555N are basically a RS flip flop with differential comparators its R (reset) and S (set) inputs as shown in figure 1. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. In this design the capacitance remains constant but the resistance can be changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable resistors and diodes. Figure ?? illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5032PWM Coltrolled Stir Plate Design2013-05-07T02:46:58Z<p>Kaiser: Kaiser moved page PWM stir plate design to PWM Coltrolled Stir Plate Design</p>
<hr />
<div>=Sirplate design=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitizes. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers havs shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or aquiring stir plates. Given the fairly high pice ($50 for a simple design and $100+ for most commercial models) many home brewers op for builing their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitates but have the capacity to hold many flasks at once. Bulding a shaker table is more complicated than a stir plate whcih is why they are not commonly used by home brewers.<br />
<br />
==Design options==<br />
<br />
Most home built stir plates use a DC fan to which stong magnets are attaches. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan spedd through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control poblem is overcome by a pulse width modulation (PMW) design which does not change the voltage applied to the fan but the amount of time during a cycle when the fan is turned on. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
==PWM design==<br />
<br />
The fan speed control logic described here is based on a Home Brew Talk post by ??? whith a few modifications. It employs a ??? timer chip. The internals og the ??? are basically a RS flip flop with differential comparators at their R (reset) and S (set) inputs as shown in figure ??. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. In this design the capacitance remains constant but the resistance can be changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable resistors and diodes. Figure ?? illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_stir_plate_design&diff=5033PWM stir plate design2013-05-07T02:46:58Z<p>Kaiser: Kaiser moved page PWM stir plate design to PWM Coltrolled Stir Plate Design</p>
<hr />
<div>#REDIRECT [[PWM Coltrolled Stir Plate Design]]</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5031PWM Coltrolled Stir Plate Design2013-05-07T02:46:31Z<p>Kaiser: </p>
<hr />
<div>=Sirplate design=<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitizes. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers havs shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or aquiring stir plates. Given the fairly high pice ($50 for a simple design and $100+ for most commercial models) many home brewers op for builing their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitates but have the capacity to hold many flasks at once. Bulding a shaker table is more complicated than a stir plate whcih is why they are not commonly used by home brewers.<br />
<br />
==Design options==<br />
<br />
Most home built stir plates use a DC fan to which stong magnets are attaches. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan spedd through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control poblem is overcome by a pulse width modulation (PMW) design which does not change the voltage applied to the fan but the amount of time during a cycle when the fan is turned on. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
==PWM design==<br />
<br />
The fan speed control logic described here is based on a Home Brew Talk post by ??? whith a few modifications. It employs a ??? timer chip. The internals og the ??? are basically a RS flip flop with differential comparators at their R (reset) and S (set) inputs as shown in figure ??. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. In this design the capacitance remains constant but the resistance can be changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable resistors and diodes. Figure ?? illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=PWM_Coltrolled_Stir_Plate_Design&diff=5030PWM Coltrolled Stir Plate Design2013-05-07T02:45:55Z<p>Kaiser: Created page with "=PWM Controlled Stir Plate= ==Sirplate design== A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinni..."</p>
<hr />
<div>=PWM Controlled Stir Plate=<br />
<br />
==Sirplate design==<br />
<br />
A stir plate uses a pair of spinning magnets to move a magnetic stir bar contained inside a flask or other vessel. The spinning of the stir bar keeps the liquid, in our case a yeast starter, agitated which promotes gas exchange and keeps the yeast in suspension. The main advantage of such a set-up is the ease with which it can be sanitizes. All surfaces that come in contact with the starter, flask and stir bar, can be sanitized through boiling.<br />
<br />
Experiments and observations by home brewers havs shown that constantly agitated starters increase yeast growth by 2 to 4 times over non agitated starters. This is the main reason why home brewers are interested in building or aquiring stir plates. Given the fairly high pice ($50 for a simple design and $100+ for most commercial models) many home brewers op for builing their own.<br />
<br />
Commercial labs often favor the use of orbital shaker tables which also keep yeast cultures agitates but have the capacity to hold many flasks at once. Bulding a shaker table is more complicated than a stir plate whcih is why they are not commonly used by home brewers.<br />
<br />
==Design options==<br />
<br />
Most home built stir plates use a DC fan to which stong magnets are attaches. The main design difference lies in how the speed of that fan is controlled. Simple designs put a variable resistor between the DC power supply and the fan. Slightly more complex designs use a linear voltage controller to regulate the voltage applied to the fan. The problem with designs that control fan spedd through voltage is that most fans have a narrow voltage band between no rotation and full speed. This makes speed control difficult unless there is sufficient resistance from the liquid that is stirred.<br />
<br />
This speed control poblem is overcome by a pulse width modulation (PMW) design which does not change the voltage applied to the fan but the amount of time during a cycle when the fan is turned on. The frequency of the pulsed fan power is generally between 10-100 Hz. A PWM based design is described by this article.<br />
<br />
An even more sophisticated stir plate control uses a micro controller and speed sensor to implement a feedback loop that allows for accurate fan speed control based on a speed (RPM) set by the user. The Digital Stirplate offered by [http://www.digitalhomebrew.com/p/52/digital-stirplate Digital Homebrew] employs such a design.<br />
<br />
==PWM design==<br />
<br />
The fan speed control logic described here is based on a Home Brew Talk post by ??? whith a few modifications. It employs a ??? timer chip. The internals og the ??? are basically a RS flip flop with differential comparators at their R (reset) and S (set) inputs as shown in figure ??. When the voltage at the THRES input exceeds the internally generated V<sub>thres</sub> the R input of the flip flop asserts high and the output is reset to 0. Conversely if the voltage at the TRIG input is lower than the internally created V<sub>trig</sub> the flip flop's S input asserts high and the output Q is asserted high. In this design TRIG and THRES are both connected to the same terminal of a capacitor and as a reslt R and S can never be asserted at the same time. <br />
<br />
Pulses of differing witdth will be created by triggering the R and S inputs at changing time intervals through charging and discharging of the capcitor. The speed which which a capacitor charges depends on the product of its capacitance and the resistor though which it is charged, also called RC constant. In this design the capacitance remains constant but the resistance can be changed.<br />
<br />
In this design the capacitor is connected to the output Q though variable resistors and diodes. Figure ?? illustrates how the capacitor is charged and discharged as a result of being connected to Q. When Q is asserted high, the cpacitor is charged through the R1 part of the potentiometer until the voltage on the capacitor reaches V<sub>thres</sub> at which point the R input of the flop is triggered and Q asserts low. Now the capacitor discharges through the R2 part of the potentiometer until the capacitor voltage falls below V<sub>trig</sub>, S is triggered and Q asserts high repeating the process of charging the capacitor. <br />
<br />
The result is that the time of Q being asserted high deepends on the product of R1 and the capacitance C while the width of Q being asserted low depends on R2 and the capacitance C. Since R1 and R2 are part of a potentiometer they are adjustable but their sum has to remain constant. What follows is that changing R1 changes the percentage that Q is asserted high but not the frequency of pulses on Q.<br />
<br />
To control the fan, Q is used to drive a MOSFET which turns the fan on and off. The longer Q is asserted high the longer the fan is turned on and thus the faster the fan will spin. The interia of the fan coulped with a sufficiently high pulse freqiency resuts in an even rotation speed despite the pulsed nature of fan's power supply.<br />
<br />
==Wiring diagram and parts list==<br />
<br />
Figure ?? shows the complete schematic for the control logic and the fan. 555 is the timer chip. D1 and D2 control whcih part of the potentiometer P1 controls charging and discharging of C1, respectively. D3 is a diode that potects the MOSFET from voltage spikes that happen when the current through the inductive load, the fan, is suddenly interrupted. Capacitors C2 and C3 stabilize the input power supply.<br />
<br />
Figure ?? shows the suggested layout on a breadboard. A standard breaboard is large enough for 2 control circuits whcih is why the option for a 2nd control circuit is shown. Pins 2 and 6 of the 555 are connected with a piece of wire under the breadboard (red dashed line) while all other connections are made with wire jumpers on top of the board (blue lines). The layout also shows the connections within the bread board for reference (thin gray lines). (+) and (-) are the 12 V power supply connections, M+ and M- are the fan terminals and M,L,R refer to the middle, left and right terminals of the potentiometer. If the fan speeds up when the potentiometer is turned to the right, simply reverse the L and R connections.<br />
<br />
===part list===<br />
<br />
The following is a part list including mouser.com item numbers. <br />
<br />
==Housing==<br />
<br />
Home brewers have been very creative when it comes to mounting the fan in a housing. As long as the top cover, which will be between the fan and the flask, any box will do. While some have even used Tupperware (R) containters they do not necissarily provide enough rigidy to support a 2 L or lager Erlenmeyer flask. I suggest using a sturdy pastic project box or custom build enclosure. The double stir plate shown here uses a simple housing fashioned from thick plywood and acryllic glass. Being able to see the spinning fan can be an advantage in some cases.<br />
<br />
==Testing & troubleshooting==<br />
<br />
The more complicated the control the more chances there are for defects. While an oscilloscope would be very useful in debugging this cicuit, a simple voltmeter will do as well. <br />
<br />
Once completed apply the 12 V supply voltage. If nothing starts smoking see if turning the potentiometer changes the fan speed. If nothing happens check the supply voltage on the 555 (pin 8) and the reset pin (pin 4). They should both be at 12 V. The check that GND (pin 1) is at 0 volt. Now pin 3. If that's at 0 V the fan should be off and when it is at 12 V the fan should be running at full speed. Now check that both pins 6 and 2 have the same voltage as pin 3. If they don't check their connections through the potentiometer.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Braukaiser.com&diff=5029Braukaiser.com2013-05-07T02:45:06Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
[[Image:Braukaiser_header.jpg]]<br />
<br />
Welcome to Braukaiser.com. This site is dedicated to brewing science and topics that are mostly related to brewing German style beers and it is not intended to be a complete reference for the home brewing process. It is a rather loose collection of various articles.<br />
<br />
'''Philosophy'''<br />
<br />
I enjoy the scientific and technological aspects brewing, which shows in the articles, and want to promote a better understanding of them as well as introduce the advanced brewer to various brewing techniques. Being an engineer I like to know what is happening and how I can control the final product and fix problems when they arise. Despite what many readers would think, I'm a fairly relaxed brewer. Some of that relaxation comes from knowing the process and knowing where attention is necessary and where not.<br />
<br />
For questions and suggestions contact '''kai at braukaiser dot com'''<br />
<br />
<br />
'''Blogs'''<br />
<br />
There are also two blogs that I'm maintaining<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Blog_general.jpg|link=http://braukaiser.com/blog/]] <br />
| [[Image:Blog_beers.jpg|link=http://braukaiser.com/blog/beers]]<br />
|-<br />
| [http://braukaiser.com/blog/ '''Braukaiser.com - Blog'''] is a convenient place to report about experiments and ramble about random subjects <br />
| [http://braukaiser.com/blog/beers/ '''Commercial Beer Reviews'''] started as a tasting report of almost 80 different beers that I had on a trip to Germany<br />
|-<br />
| 10-9-12 [http://braukaiser.com/blog/blog/2012/10/08/yeast-growth-experiments-some-early-results/ Yeast growth experiments - some early results]<br />
<br />
10-03-12 [http://braukaiser.com/blog/blog/2012/10/03/yeast-un-flocculation-for-cell-counting/ Yeas un-flocculation for cell counting]<br />
<br />
09-16-12 [http://braukaiser.com/blog/blog/2012/09/16/enzymes-in-the-fermenter/ Enzymes in the fermenter]<br />
<br />
09-09-12 [http://braukaiser.com/blog/blog/2012/09/09/hops-from-a-can/ Hops From A Can]<br />
| <br />
|}<br />
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'''Icons'''<br />
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More recent articles on this site use symbols on the right margins to indicate the type of content and allow readers to skip possibly uninteresting or complex part<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Icon_basics.gif|link=|alt={Brewing Basics}]]<br />
|'''Brewing Basics:''' The building blocks stand for basic stuff that is important for the understanding of further discussions and elaborations.<br />
|- <br />
| valign="top" | [[Image:Icon_inner_workings.gif|link=|alt={How Things Work}]]<br />
|'''How Things Work:''' the cogs mark sections that detail how a particular process woks<br />
|-<br />
| valign="top" | [[Image:Icon_brewing_advice.gif|link=|alt={Practical Brewing Advice}]]<br />
|'''Practical Brewing Advice:''' The pot stands for practical brewing advice that will help you in home brewing. Oftentimes a conclusion that is drawn from preceding, more complex, content.<br />
|-<br />
| valign="top" | [[Image:Icon_science.gif|link=|alt={Geeky Stuff}]]<br />
|'''Geeky Stuff:''' The test tube stands for geeky content. Something that is cool to know but has only little importance in practical home brewing.<br />
|}<br />
<br />
<br />
=What’s New=<br />
<br />
* '''Mar 2013''' - added [[Lactate Taste Threshold experiment]]<br />
* '''Oct 2012''' - added [[Microscope use in brewing]]<br />
* '''Apr 2012''' - added [[Yeast Propagator]]<br />
* '''Mar 2012''' - added [[Beer color to mash pH (v2.0)]]<br />
* '''Jul 2011''' - fixed the images that got lost after some post-hacking clean-up<br />
* '''Feb 2011''' - added [[Mash pH control]]<br />
* '''Feb 2011''' - added [[Iodine Test]]<br />
* '''Jan 2011''' - added [[A simple Model for pH Buffers]]<br />
* '''Jun 2010''' - published [http://braukaiser.com/download/Troester_NHC_2010_Efficiency.pdf NHC 2010 presentation about efficiency and how to keep it predictable]<br />
* '''Jun 2010''' - added documentation for the [[Batch Sparge and Party Gyle Simulator]]<br />
* '''May 2010''' - added [[How to read a water report]]<br />
* '''Mar 2010''' - released [[Alkalinity reduction with slaked lime]]<br />
* '''Feb 2010''' - released [[Beer color, alkalinity and mash pH]]<br />
* '''Jan 2010''' - added [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
* '''Jan 2010''' - revised and updated [[Kraeusening]]<br />
<br />
= Preparation =<br />
* [[Keeping Log]]<br />
* [[Carboy Washer]]<br />
<br />
= (Brewing) Science Basics =<br />
<br />
* Everything you need to know about pH in brewing<br />
** '''pH part 1''': [[An Overview of pH]]<br />
*** [[A simple Model for pH Buffers]]<br />
*** [[pH Meter Buying Guide]]<br />
*** [[An Evaluation of the suitability of colorpHast strips for pH measurements in home brewing]]<br />
** '''pH part 2''': [[How pH affects brewing]]<br />
** '''pH part 3''': [[Mash pH control]]<br />
*** [[Residual Alkalinity illustrated]]<br />
** [[Beer color, alkalinity and mash pH]]<br />
** [[Beer color to mash pH (v2.0)]]<br />
* [http://braukaiser.com/documents/effect_of_water_and_grist_on_mash_pH.pdf Effect of water and grist on mash pH (paper)]<br />
* [[Lactate Taste Threshold experiment]]<br />
<br />
=Ingedients=<br />
<br />
* Water<br />
** [[How to read a water report]]<br />
** [[At home water testing]]<br />
** [[Building brewing water with dissolved chalk]]<br />
** [[Alkalinity reduction with lime]]<br />
** [http://braukaiser.com/documents/Kaiser_water_calculator.xls Kaiser_water_calculator.xls] | [http://braukaiser.com/documents/Kaiser_water_calculator_US_units.xls Kaiser_water_calculator_US_units.xls]<br />
<br />
= Wort Production =<br />
<br />
* [[CrushEval|Evaluating the Crush of the Grain]]<br />
* [[Malt Conditioning]]<br />
* [[The Science of Mashing]]<br />
** [[Enzymes]]<br />
** [[Carbohydrates]]<br />
** [[Starch Conversion]]<br />
* [[The Theory of Mashing]] - revised and largely replaced by [[The Science of Mashing]]<br />
** Experiment: [[Mash Time Dependency of Wort Fermentability]]<br />
** Experiment: [[Effects of mash parameters on fermentability and efficiency in single infusion mashing]]<br />
* [[Infusion Mashing]]<br />
* [[Decoction Mashing]]<br />
* [[Batch Sparging Analysis]]<br />
* [[Iodine Test]]<br />
* [[Understanding Efficiency]]<br />
* [[Troubleshooting Brewhouse Efficiency]]<br />
* [[Batch Sparge and Party Gyle Simulator]]<br />
<br />
= Boiling and Wort Transfer =<br />
<br />
* [[Whirlpooling]]<br />
<br />
= Fermentation =<br />
* [[Understanding Attenuation]]<br />
* [[Fast Ferment Test]]<br />
* [[Fermenting Lagers]]<br />
* [[Drauflassen]]<br />
* [[Carbonation Tables]]<br />
* [[Kraeusening]]<br />
* [[Accurately Calculating Sugar Additions for Carbonation]]<br />
* '''Yeast Culturing'''<br />
** [[Yeast culturing gear]]<br />
** [[Making Plates and Slants]]<br />
** [[Inoculating Plates and Slants]]<br />
** [[Growing Yeast from a Plate]]<br />
** [[Yeast Propagator]]<br />
** [[Yeast Bank contents]]<br />
** [[Microscope use in brewing]]<br />
** [[PWM stir plate design]]<br />
* '''Experiments'''<br />
** [[Experiment Pitching Rate and Oxygenation|Pitching Rate and Oxygenation]]<br />
<br />
=Bottling/Kegging/Serving=<br />
<br />
* [[Kompensatorzapfhahn]]<br />
<br />
= Breweries =<br />
===Germany===<br />
* [[Museums- und Traditionsbrauerei Wippra|Museums- und Traditionsbrauerei Wippra (museum and traditonal brewery Wippra), Germany]]<br />
* [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
===History===<br />
* German Brewing between 1850 and 1900<br />
** Part I: [[German Brewing between 1850 and 1900 : Malting and Wort Production|Malting and Wort Production]]<br />
** Part II: [[German Brewing between 1850 and 1900: Fermentation and Beer|Fermentation and Beer]]<br />
<br />
= Literature =<br />
<br />
= Misc =<br />
* [[Links]]<br />
* [[Recipes]]<br />
** [[Various water recipes]]<br />
** Obergäriges (Ales)<br />
*** [[Kaiser Alt]]<br />
*** [[Weissbier Hell]]<br />
** Untergäriges (Lagers)<br />
*** [[Dunkel]]<br />
*** [[Schwarzbier]]<br />
*** [[Maibock]]<br />
*** [[Imperator|Imperator (Doppelbock)]]<br />
*** [[Edel Hell]]<br />
** Food<br />
*** [[Treberbrot]]<br />
*** [[Brezels and other Laugengebäck]]<br />
* [[Glossary of German Brewing Terms]]<br />
* [[Tables for Conversions and Calculations]]<br />
* [[Foreign Content]]<br />
* [[Podcasts]]<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Braukaiser.com&diff=5028Braukaiser.com2013-03-11T04:04:32Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
[[Image:Braukaiser_header.jpg]]<br />
<br />
Welcome to Braukaiser.com. This site is dedicated to brewing science and topics that are mostly related to brewing German style beers and it is not intended to be a complete reference for the home brewing process. It is a rather loose collection of various articles.<br />
<br />
'''Philosophy'''<br />
<br />
I enjoy the scientific and technological aspects brewing, which shows in the articles, and want to promote a better understanding of them as well as introduce the advanced brewer to various brewing techniques. Being an engineer I like to know what is happening and how I can control the final product and fix problems when they arise. Despite what many readers would think, I'm a fairly relaxed brewer. Some of that relaxation comes from knowing the process and knowing where attention is necessary and where not.<br />
<br />
For questions and suggestions contact '''kai at braukaiser dot com'''<br />
<br />
<br />
'''Blogs'''<br />
<br />
There are also two blogs that I'm maintaining<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Blog_general.jpg|link=http://braukaiser.com/blog/]] <br />
| [[Image:Blog_beers.jpg|link=http://braukaiser.com/blog/beers]]<br />
|-<br />
| [http://braukaiser.com/blog/ '''Braukaiser.com - Blog'''] is a convenient place to report about experiments and ramble about random subjects <br />
| [http://braukaiser.com/blog/beers/ '''Commercial Beer Reviews'''] started as a tasting report of almost 80 different beers that I had on a trip to Germany<br />
|-<br />
| 10-9-12 [http://braukaiser.com/blog/blog/2012/10/08/yeast-growth-experiments-some-early-results/ Yeast growth experiments - some early results]<br />
<br />
10-03-12 [http://braukaiser.com/blog/blog/2012/10/03/yeast-un-flocculation-for-cell-counting/ Yeas un-flocculation for cell counting]<br />
<br />
09-16-12 [http://braukaiser.com/blog/blog/2012/09/16/enzymes-in-the-fermenter/ Enzymes in the fermenter]<br />
<br />
09-09-12 [http://braukaiser.com/blog/blog/2012/09/09/hops-from-a-can/ Hops From A Can]<br />
| <br />
|}<br />
<br />
<br />
<br />
<br />
'''Icons'''<br />
<br />
More recent articles on this site use symbols on the right margins to indicate the type of content and allow readers to skip possibly uninteresting or complex part<br />
<br />
{| style="width:800px"<br />
|-<br />
| valign="top" | [[Image:Icon_basics.gif|link=|alt={Brewing Basics}]]<br />
|'''Brewing Basics:''' The building blocks stand for basic stuff that is important for the understanding of further discussions and elaborations.<br />
|- <br />
| valign="top" | [[Image:Icon_inner_workings.gif|link=|alt={How Things Work}]]<br />
|'''How Things Work:''' the cogs mark sections that detail how a particular process woks<br />
|-<br />
| valign="top" | [[Image:Icon_brewing_advice.gif|link=|alt={Practical Brewing Advice}]]<br />
|'''Practical Brewing Advice:''' The pot stands for practical brewing advice that will help you in home brewing. Oftentimes a conclusion that is drawn from preceding, more complex, content.<br />
|-<br />
| valign="top" | [[Image:Icon_science.gif|link=|alt={Geeky Stuff}]]<br />
|'''Geeky Stuff:''' The test tube stands for geeky content. Something that is cool to know but has only little importance in practical home brewing.<br />
|}<br />
<br />
<br />
=What’s New=<br />
<br />
* '''Mar 2013''' - added [[Lactate Taste Threshold experiment]]<br />
* '''Oct 2012''' - added [[Microscope use in brewing]]<br />
* '''Apr 2012''' - added [[Yeast Propagator]]<br />
* '''Mar 2012''' - added [[Beer color to mash pH (v2.0)]]<br />
* '''Jul 2011''' - fixed the images that got lost after some post-hacking clean-up<br />
* '''Feb 2011''' - added [[Mash pH control]]<br />
* '''Feb 2011''' - added [[Iodine Test]]<br />
* '''Jan 2011''' - added [[A simple Model for pH Buffers]]<br />
* '''Jun 2010''' - published [http://braukaiser.com/download/Troester_NHC_2010_Efficiency.pdf NHC 2010 presentation about efficiency and how to keep it predictable]<br />
* '''Jun 2010''' - added documentation for the [[Batch Sparge and Party Gyle Simulator]]<br />
* '''May 2010''' - added [[How to read a water report]]<br />
* '''Mar 2010''' - released [[Alkalinity reduction with slaked lime]]<br />
* '''Feb 2010''' - released [[Beer color, alkalinity and mash pH]]<br />
* '''Jan 2010''' - added [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
* '''Jan 2010''' - revised and updated [[Kraeusening]]<br />
<br />
= Preparation =<br />
* [[Keeping Log]]<br />
* [[Carboy Washer]]<br />
<br />
= (Brewing) Science Basics =<br />
<br />
* Everything you need to know about pH in brewing<br />
** '''pH part 1''': [[An Overview of pH]]<br />
*** [[A simple Model for pH Buffers]]<br />
*** [[pH Meter Buying Guide]]<br />
*** [[An Evaluation of the suitability of colorpHast strips for pH measurements in home brewing]]<br />
** '''pH part 2''': [[How pH affects brewing]]<br />
** '''pH part 3''': [[Mash pH control]]<br />
*** [[Residual Alkalinity illustrated]]<br />
** [[Beer color, alkalinity and mash pH]]<br />
** [[Beer color to mash pH (v2.0)]]<br />
* [http://braukaiser.com/documents/effect_of_water_and_grist_on_mash_pH.pdf Effect of water and grist on mash pH (paper)]<br />
* [[Lactate Taste Threshold experiment]]<br />
<br />
=Ingedients=<br />
<br />
* Water<br />
** [[How to read a water report]]<br />
** [[At home water testing]]<br />
** [[Building brewing water with dissolved chalk]]<br />
** [[Alkalinity reduction with lime]]<br />
** [http://braukaiser.com/documents/Kaiser_water_calculator.xls Kaiser_water_calculator.xls] | [http://braukaiser.com/documents/Kaiser_water_calculator_US_units.xls Kaiser_water_calculator_US_units.xls]<br />
<br />
= Wort Production =<br />
<br />
* [[CrushEval|Evaluating the Crush of the Grain]]<br />
* [[Malt Conditioning]]<br />
* [[The Science of Mashing]]<br />
** [[Enzymes]]<br />
** [[Carbohydrates]]<br />
** [[Starch Conversion]]<br />
* [[The Theory of Mashing]] - revised and largely replaced by [[The Science of Mashing]]<br />
** Experiment: [[Mash Time Dependency of Wort Fermentability]]<br />
** Experiment: [[Effects of mash parameters on fermentability and efficiency in single infusion mashing]]<br />
* [[Infusion Mashing]]<br />
* [[Decoction Mashing]]<br />
* [[Batch Sparging Analysis]]<br />
* [[Iodine Test]]<br />
* [[Understanding Efficiency]]<br />
* [[Troubleshooting Brewhouse Efficiency]]<br />
* [[Batch Sparge and Party Gyle Simulator]]<br />
<br />
= Boiling and Wort Transfer =<br />
<br />
* [[Whirlpooling]]<br />
<br />
= Fermentation =<br />
* [[Understanding Attenuation]]<br />
* [[Fast Ferment Test]]<br />
* [[Fermenting Lagers]]<br />
* [[Drauflassen]]<br />
* [[Carbonation Tables]]<br />
* [[Kraeusening]]<br />
* [[Accurately Calculating Sugar Additions for Carbonation]]<br />
* '''Yeast Culturing'''<br />
** [[Yeast culturing gear]]<br />
** [[Making Plates and Slants]]<br />
** [[Inoculating Plates and Slants]]<br />
** [[Growing Yeast from a Plate]]<br />
** [[Yeast Propagator]]<br />
** [[Yeast Bank contents]]<br />
** [[Microscope use in brewing]]<br />
* '''Experiments'''<br />
** [[Experiment Pitching Rate and Oxygenation|Pitching Rate and Oxygenation]]<br />
<br />
=Bottling/Kegging/Serving=<br />
<br />
* [[Kompensatorzapfhahn]]<br />
<br />
= Breweries =<br />
===Germany===<br />
* [[Museums- und Traditionsbrauerei Wippra|Museums- und Traditionsbrauerei Wippra (museum and traditonal brewery Wippra), Germany]]<br />
* [[Museumsbrauerei Schmitt| Museumsbrauerei Schmitt, Singen, Germany]]<br />
<br />
===History===<br />
* German Brewing between 1850 and 1900<br />
** Part I: [[German Brewing between 1850 and 1900 : Malting and Wort Production|Malting and Wort Production]]<br />
** Part II: [[German Brewing between 1850 and 1900: Fermentation and Beer|Fermentation and Beer]]<br />
<br />
= Literature =<br />
<br />
= Misc =<br />
* [[Links]]<br />
* [[Recipes]]<br />
** [[Various water recipes]]<br />
** Obergäriges (Ales)<br />
*** [[Kaiser Alt]]<br />
*** [[Weissbier Hell]]<br />
** Untergäriges (Lagers)<br />
*** [[Dunkel]]<br />
*** [[Schwarzbier]]<br />
*** [[Maibock]]<br />
*** [[Imperator|Imperator (Doppelbock)]]<br />
*** [[Edel Hell]]<br />
** Food<br />
*** [[Treberbrot]]<br />
*** [[Brezels and other Laugengebäck]]<br />
* [[Glossary of German Brewing Terms]]<br />
* [[Tables for Conversions and Calculations]]<br />
* [[Foreign Content]]<br />
* [[Podcasts]]<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5027Lactate Taste Threshold experiment2013-03-11T04:03:18Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
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<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. "Brewing: Science and Practice" lists a lactic acid taste threshold of 400 mg/l<ref name="Briggs">Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes, Roger Stevens, ''Brewing Science and Practice'', Published by Woodhead Publishing, 2004</ref>. No detail is given about the experiments. It's unknown if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
Narziss and Back mention acidulated malt additions at levels as high as 8% to neutralize water alkalinity and lower the mash pH to a desirable level of 5.5 - 5.6<ref name="Narziss_Back">Ludwig Narziss, Werner Back, Die Bierbrauerei Band 2: Technologie der Würzebereitung, Wiley-VCH, 2009</ref>. For a 12 Plato beer brewed with 95% efficiency into kettle this adds 380 mg/l lactate to the beer.<br />
<br />
A common upper bound of acid malt use given by home brewers is 4-5%. <br />
<br />
To answer the question of taste threshold of lactate in water and beer I conducted a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into one group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample was the control.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser and Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and water. It was important for this experiment that the addition of lactate did not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the repective water or beer sample. If the pH was too high a bit more lactic acid solution was added to bring it down again. By doing so the lactate/lactic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total addition of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concentration (mg/l) !! equivalent amount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> the equivalent amount of acidulated malt assumes an efficiency into the kettle of 85% and a lactic acid content of 3% (w/w) for the acidulated malt.<br />
<br />
Samples were assigned random letters with the exception of 0, which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most added lactate. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets. An intensity of 0 was assigned to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. <br />
<br />
To account for this I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts in Figure 2.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2 - scaled flavor intensity was determined by using the lactate level of the sample that a given panelist reported as tasting the most intense as the upper limit for that panelist.]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise. Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty identifying the flavor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamiliar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelists had general difficulties identifying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings (5) over the 200-1200 mg/l range in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more easily detectable in water than in beer. It seems logical that more intensive beer flavors would be able to mask higher levels of lactate, however, more experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 3 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations is not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook other beer flavors for the off flavor. Palate fatigue is also an issue in this experiment due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an equivalent acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A general recommendation for home brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate in a 12 Plato beer with 85% efficiency into kettle. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidulated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<references/><br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5026Lactate Taste Threshold experiment2013-03-11T01:15:25Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. "Brewing: Science and Practice" lists a lactic acid taste threshold of 400 mg/l<ref name="Briggs">Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes, Roger Stevens, ''Brewing Science and Practice'', Published by Woodhead Publishing, 2004</ref>. No detail is given about the experiments. It's unknown if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
Narziss and Back mention acidulated malt additions at levels as high as 8% to neutralize water alkalinity and lower the mash pH to a desirable level of 5.5 - 5.6<ref name="Narziss_Back">Ludwig Narziss, Werner Back, Die Bierbrauerei Band 2: Technologie der Würzebereitung, Wiley-VCH, 2009</ref>. For a 12 Plato beer brewed with 95% efficiency into kettle this adds 380 mg/l lactate to the beer.<br />
<br />
A common upper bound of acid malt use given by home brewers is 4-5%. <br />
<br />
To answer the question of taste threshold of lactate in water and beer I conducted a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into one group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample was the control.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<br />
<references/><br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5025Lactate Taste Threshold experiment2013-03-10T14:54:14Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. Brewing: Science and Practice lists a lactic acid taste threshold of 400 mg/l<ref name="Briggs">Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes, Roger Stevens, ''Brewing Science and Practice'', Published by Woodhead Publishing, 2004</ref>. No detail is given if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
Narziss and Back mention acidulated malt additions at levels as high as 8% to neutralize water alkalinity and lower the mash pH to a desirable level of 5.5 - 5.6<ref name="Narziss_Back">Ludwig Narziss, Werner Back, Die Bierbrauerei Band 2: Technologie der Würzebereitung, Wiley-VCH, 2009</ref>. For a 12 Plato beer brewed with 95% efficiency into kettle this adds 380 mg/l lactate to the beer.<br />
<br />
A common upper bound of acid malt use given by home brewers is 4-5%. <br />
<br />
To answer the question of taste threshold of lactate in water and beer I conducted a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample was the control.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<br />
<references/><br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5024Lactate Taste Threshold experiment2013-03-10T14:44:31Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. Brewing: Science and Practice lists a lactic acid taste threshold of 400 mg/l<ref>Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes, Roger Stevens, ''Brewing Science and Practice'', Published by Woodhead Publishing, 2004</ref>. No detail is given if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
<br />
<br />
<br />
<br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<br />
<references/><br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5023Lactate Taste Threshold experiment2013-03-10T14:42:11Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. Brewing: Science and Practice lists a lactic acid taste threshold of 400 mg/l. No detail are given if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
<br />
<br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<ref>test ref</ref><br />
<br />
<references/><br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5022Lactate Taste Threshold experiment2013-03-10T14:41:37Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Home brewers are using it in the form of acidulated malt or 88% concentrated lactic acid. A common concern with lactic acid is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer while the mash pH is still in the desired range ?<br />
<br />
The literature provides little information on this topic. Brewing: Science and Practice lists a lactic acid taste threshold of 400 mg/l. No detail are given if during these experiments the lactic acid was neutralized. This aspect is important since the sour taste of lactic acid comes from its ability to lower pH. When neutralized to the pH of the sample in which it is tasted lactic acid is more difficult to detect.<br />
<br />
<br />
<br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
= References =<br />
<br />
<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5021Lactate Taste Threshold experiment2013-03-10T14:10:32Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[[File:LactateTaste_charts_3.gif|frame|center|Figure 3 - The highest level of added lactate that was a given panelists reported as tasting like the control. The higher the bars the more difficult it was to detect the lactate]] <br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5020Lactate Taste Threshold experiment2013-03-10T14:03:41Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif|frame|center|Figure 1 - The off-flavor rating given to the different samples by the 8 panelists. Samples reported as tasting like the control are shown as 0 while the sample with the most noticeable off-flavor is shown as 5. See text for further detail]]<br />
<br />
[[File:LactateTaste_charts_2.gif|frame|center|Figure 2]] <br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5019Lactate Taste Threshold experiment2013-03-10T13:56:21Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[[File:LactateTaste_charts_1.gif]]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5018Lactate Taste Threshold experiment2013-03-10T13:55:07Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
<nowiki>*</nowiki> Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[Figure 1]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5017Lactate Taste Threshold experiment2013-03-10T13:53:46Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 <br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) <br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) <br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) <br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) <br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) <br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) !! equivalent aount of acidulated malt for 12 Plato beer*<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 || 0%<br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
* Assumes an efficiency into the kettle of 85%<br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[Figure 1]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5016Lactate Taste Threshold experiment2013-03-10T13:51:48Z<p>Kaiser: </p>
<hr />
<div>{| style="width:800px"<br />
|<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) || equivalent aount of acidulated malt for 12 Plato beer<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 || 0%<br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 <br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) <br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) <br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) <br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) <br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) <br />
|} <br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[Figure 1]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.<br />
<br />
|}</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5015Lactate Taste Threshold experiment2013-03-10T13:51:07Z<p>Kaiser: </p>
<hr />
<div><br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) || equivalent aount of acidulated malt for 12 Plato beer<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 || 0%<br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 <br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) <br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) <br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) <br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) <br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) <br />
|} <br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
= Results and Discussion =<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[Figure 1]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
= Conclusion =<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment&diff=5014Lactate Taste Threshold experiment2013-03-10T13:50:37Z<p>Kaiser: Created page with "=Lactate Taste Threshold Experiment= Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt ..."</p>
<hr />
<div>=Lactate Taste Threshold Experiment=<br />
<br />
Lactic acid is a very popular acid for brewing water treatment and mash pH correction. Brewers may use it in the form of acidulated malt or 88% concentrated lactic acid. The concern with lactic acid, however, is its impact on the final beer flavor when rather large amounts are used. Lactic acid is associated with sour beers and that flavor may not be welcome in a Pilsner style beer, for example.<br />
<br />
The question many brewers are struggling with is: How much lactic acid is needed to make a negative impact on the flavor of the beer ?<br />
<br />
The literature provides little information on this topic. Brewing and Malting Science <br />
<br />
To answer this question I set out to conduct a taste experiment with 8 members of my home brew club [http://www.bfd.org Brew Free or Die] as panelists. Each panelists received 4 sets of 6 different samples and was asked to sort them into a group in which the off flavor is not detectable and sort the rest by the intensity of that flavor. The panelists were not told what the off flavor is but knew which sample did not contain it.<br />
<br />
= Materials and Methods=<br />
<br />
The four sets of samples were water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale. I added increasing amounts of calcium lactate to these beers and the water. It was important for this experiment that the addition of lactate does not change the pH of the sample which is why I prepared a 23 g/l lactic acid solution by adding 8.25 ml 88% lactic acid to 375 ml reverse osmosis water. A sample of that solution was taken and dry slaked lime (Ca(OH)<sub>2</sub>) was added until it reached the pH of the sample to which it was added. If the pH was too high a bit more of the latic acid solution was added to bring it down again. By doing so the lactate/latic acid concentration did not change.<br />
<br />
The resulting solution was then added to the samples. For the beers a mix of water and Ca-lactate solution was added to keep the total adding of water the same.<br />
<br />
Water<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l) || equivalent aount of acidulated malt for 12 Plato beer<br />
|- <br />
| 0 || 600 || 0 || 0 || 0 || 0%<br />
|- <br />
| 1 || 600 || 0 || 5 || 193 (labeled 200) || 3.7%<br />
|- <br />
| 2 || 600 || 0 || 10 || 387 (labeled 400) || 7.3%<br />
|- <br />
| 3 || 600 || 0 || 18 || 696 (labeled 700) || 13.2%<br />
|- <br />
| 4 || 600 || 0 || 25 || 968 (labeled 1000) || 18.3%<br />
|- <br />
| 5 || 600 || 0 || 35 || 1239 (labeled 1200) || 23.4%<br />
|} <br />
<br />
Bud Light, Budweiser and Sierra Nevada Torpedo<br />
<br />
{| class="wikitable" <br />
|- <br />
! sample ID !! volume (ml) !! water added (ml) !! Ca-lactate added (ml) !! resulting lactate concetration (mg/l)<br />
|- <br />
| 0 || 350 || 18.7 || 0 || 0 <br />
|- <br />
| 1 || 350 || 15.8 || 2.9 || 193 (labeled 200) <br />
|- <br />
| 2 || 350 || 12.8 || 5.8 || 387 (labeled 400) <br />
|- <br />
| 3 || 350 || 8.2 || 10.5 || 696 (labeled 700) <br />
|- <br />
| 4 || 350 || 4.1 || 14.6 || 968 (labeled 1000) <br />
|- <br />
| 5 || 350 || 0 || 18.7 || 1239 (labeled 1200) <br />
|} <br />
<br />
Samples were then assigned random letters with the exception of 0 which always received letter A. Each panelist received a score sheet on which he/she would note which samples taste like A and the intensity ranking of the off-flavor in the other samples.<br />
<br />
Samples were presented in this order: water, Bud Light, Budweiser, Sierra Nevada Torpedo Ale.<br />
<br />
Some of the panelists were BJCP certified judges.<br />
<br />
== Results and Discussion ==<br />
<br />
One theme apparent during tasting was how much difficulty panelists had in consistently identifying the samples with the most lactate added. This provided a challenge in deriving trends from the taste results.<br />
<br />
Figure 1 shows the tasting results for the 4 sets plotted as absolute and ajusted results. For the absolute results I assigned an intensity of 0 to all samples that a given panelist indicated as tasting like the control. The sample with the most intense flavor was assigned a 5, the second most intense a 4 and so forth. The problem with this approach is that many panelists did not identify the sample with the most lactate added as the one with the most intense off flavor. Panelist 6, for example noted that the water with 200 ppm lactate tasted most intense. To correct for that I took the lactate level of the sample that was noted as having the most intense "off-flavor" and used it as the level for the most intense tasting sample indicated by that taster. The intensities of the other samples were then scaled based on that. That resulted in the charts on the left hand side in Figure 1.<br />
<br />
[Figure 1]<br />
<br />
Just by looking at the density and height of bars, lactate is more easily detected in water. This does not come as a surprise.Some identified it down to a level of 200 mg/l, while some where not able to detect it until it reached levels of 700 mg/l.<br />
<br />
Panelists had more difficulty indentifying the flaor in the 3 beers that were presented. To my surprise Bud Light did the best job of hiding this flavor. This may have been the result of panelists being unfamililar with the taste of this beer, something that should also be true for Budweiser, or that it was the first flight of beer they were presented with.<br />
<br />
Another explanation is that panelits had general difficulties indetifiying the flavors in the beers even when the highest amount added was 1200 mg/l. This becomes evident by the rather even spread of high ratings over the 200-1200 mg/l range on the left hand side in Figure 1. In water those higher bars are more clustered toward the higher lactate range.<br />
<br />
Based on this and having tasted lactate in Budweiser myself, I'm willing to conclude that it is fairly difficult to detect added lactate at a level of 400 or below.<br />
<br />
This experiment was not able to show that the intensity of the beer flavor changes the perception threshold for additional lactate, although it showed that it is more esily detectable in water than in beer. That would lead to the conclusion that more intensitve beer flavors would be able to mask higher levels of lactate. More experimentation is needed for this, in particular the maximum lactate level should be raised to allow it to stand out more prominently as many panelists misidentified the sample with the most lactate added.<br />
<br />
Figure 2 is yet another way to look at the results. For each series and panelist it shows the highest level of lactate that was marked as tasting like the control. The correlations os not very strong but it shows that lactate was more easily detected in water. The high bars for Bud Light show that panelists had trouble detecting lactate in that beer. While generally low bars for Budweiser and Sierra Nevada Torpedo suggest that it was easier to detect in these beers. However, this is likely a random error since the low correlation between actual lactate levels and flavor rating suggests that most panelists ended up guessing or mistook over beer flavors for the off flavor. Palate fatigue is also an issue in these experimend due to the fairly large number of samples that were tasted.<br />
<br />
[Figure 2]<br />
<br />
== Conclusion ==<br />
<br />
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A genereal recommendation for brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate if a 12 Plato beer with 85% efficiency into kettle is assumed. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidilated malt won't ruin a beer if that amount is needed to counteract water alkalinity.</div>Kaiserhttp://braukaiser.com/wiki/index.php?title=Sandbox&diff=5013Sandbox2013-03-10T13:49:59Z<p>Kaiser: </p>
<hr />
<div>{| style="width:850px" border="0"<br />
<br />
<br />
[[Lactate Taste Threshold experiment]]<br />
<br />
<br />
<br />
test <ref>test ref</ref><br />
<br />
<references/><br />
<br />
|}</div>Kaiser