NHC 2013 presentation

My presentation at the NHC today was very well received. Yeast growth in starters does interest a lot of brewers and I had a lot of new data to present. Now that I finished the presentation I can devote more time on experiment documentation here on braukaiser.com.

A copy of the presentation can be found here.

Starter Wort Gravity and Yeast Growth

This is an experiment I conducted a few weeks ago. It examines the effect that the starer original gravity has on yeast growth. Only yeast growth and viability based on methylene blue staining were examined.

Experiment Setup

For this experiment a 20 Plato wort was prepared from DME and inoculated with a culture of WLP 036 (Duesseldorf Altbier) at a rate of about 0.04 B/g. After inoculation and thorough mixing the wort was divided into four 500 ml flask. Each flask received about 100 g of the 20 Plato wort. To 3 of the 4 flasks additional water was added. The amount of water added was 100 g, 200 g and 300 g, respectively.


Yeast Growth

The following chart plots the specific growth in Billion per gram of extract (B/g) for the 4 different experiments. WortOGAndYeastGrowthWhile the 20 P/100 ml experiment was able to develop the best vortex due to the lower wort level, it’s growth was significantly less than that of the other experiments with lower gravity and higher wort levels.  Yeast growth saturates at 3 B/g but from this experiment it is not apparent if this limitation is caused by the culture’s access to air or another limiting nutrient. That other limiting nutrient could be nitrogen.

During propagation hardly any vortex was visible in the 5 P/400 ml starter due to a volume that approached the capacity of the flask (500 ml) yet it still showed the same growth as the 10 P/ 200 ml experiment where the vortex was able to draw in more air. A previous experiment (Stir Speed and Yeast Growth) showed yeast growth changes as the stir speed and with it the size of the vortex changes. However, this experiment was done with a different yeast (WY2042) and the yeast used here (WLP036) may hit maximum growth in wort with lower oxygen uptake than WY2042.

Culture Viability

When the growth yeast populations were stained with methylene blue to asses their viability slight differences were noticeable.

20 Plato starter

20 Plato starter

10 Plato starter

10 Plato starter

7 Plato starter

7 Plato starter

5 Plato starter

5 Plato starter

Yeast grown in the 20 Plato starter showed a viability of about 90% while populations from the other 3 starters had close to 100% viability.  That was to be expected given the toxicity of high alcohol environments on yeast cells.



The experiment did not uncover much new information. It showed that high gravity worts but lower starter volumes to not result in the same amount of yeast growth compared to a lower gravity starter with more volume despite their potentially improved access to O2. Furthermore, the resulting higher alcohol concentration in high gravity starters is likely to reduce the viability of the culture.


Yeast Growth and the Question of Quality vs. Quantity

In the Fermentation Test for Starter and Air Access Experiment I showed results that suggested that quantity in yeast growth does not necessarily mean best fermentation performance. I repeated these experiments with a different yeast (WLP 036, Duesseldorf Alt) and a pattern seems to be emerging. Like WY2042, WLP036 is a poor flocculator, which makes cell counting easier. Unlike WY2042, it is an ale yeast.

Below is a chart showing the specific yeast growth (Billion cells grown per gram of extract) plotted for 4 different starter configurations:

  • airlock, no access to air, except for what was in the head space
  • aluminum foil, loosely crimped
  • cotton ball to emulate a breathable stopper
  • open: no cover on the flask. This should be seen as best case for passive gas exchange but it is not necessarily practical for yeast propagation due to contamination concerns


Yeast growth over different propagation conditions

Qualitatively these results are very similar to the same experiment done with WY2042 as shown here. The open flask leads to an increase of about 40% over the airlock covered flask. But WL036  is able to grow more yeast per gram of extract compared to  WY2042. These are strain to strain variations that have to be examined in a different experiment.


Just like in the previous experiment the yeast grown in this experiment was used to ferment a high gravity wort. The original gravity was increased to 30 Plato (~ 1.130 sg) in order to increase the stress on the yeast. Just as before, the wort was prepared from dried malt extract (Briess extract light DME).

Once again the yeast with the least access to air took off the fastest as can be seen in the following plot of weight loss over the first 7 days:

Weight drop during the first 7 days of the fermentation test

But this time fermentation slowed down significantly well before the 80% attenuation limit of the wort. Based on the weight drop fermentation slowed down significantly at about 40% ADF (Apparent Degree of Fermentation). This time all the fermentation experiments were conducted in 500 ml flasks covered with an air lock. This does seem to lead to a better correlation between weight loss and attenuation.

On day 6 a refractometer reading was done on all 4 experiments and the result correlated with the weight loss at that time. In addition to the refractometer reading the health of the yeast population was assessed with methylene blue staining and all 4 yeast populations. The “airlock” yeast population showed about 10% lower viability (more stained cells) compared to the other 3 populations which showed virtually no stained cells:


Micrograph of a methylene blue stained yeast sample from the “airlock” fermentation test 6 days after pitching the yeast. About 10% of the cells stained with MB.


Micrograph of a yeast sample from the “foil” fermentation test stained with methylene blue at day 6 after pitching. The “cotton ball” and “open” experiments also showed virtually no stained cells.


During an additional 2 weeks of fermentation, the yeast propagated with air lock cover remained stalled at about 5% weight loss while other yeast populations were able to pull ahead, albeit much slower than they did during the first 4 days.


Weight loss during 21 days of fermentation

After 21 days the yeast covered with a cotton ball during propagation is showing the most attenuation so far.

The comparatively poor performance of the yeast grown with an open flask, which showed the most growth per initial extract, points to the conclusion that more growth during propagation is not necessarily better. At this point I suspect 2 mechanisms that could be at work here

  1. yeast propagated with an open flask has access to too much air and as a result becomes less efficient at working in a completely anaerobic environment. If this is the case yeast companies should not propagate yeast in aerobic environments, yet they do.
  2. While more oxygen during yeast growth allows for more growth, the amount of available nitrogen is limited. As a result yeast gown at a high growth rate without supplemental nitrogen will be nitrogen deprived which largely affects their protein level. This may lead to less efficient metabolism thus the slower fermentation rate that was observed.

I suspect that it is the reduces nitrogen level that causes the yeast poorly during the initial phase of fermentation. To test that I plan to repeat this experiment with the following 4 yeast propagation conditions:

  • airlock covered
  • airlock covered + DAP (diammonium phosphate) as an added nitrogen source
  • open
  • open + DAP


Posted Wiki Article on Building a PWM Controlled Stir Plate

I finally finished an article on building a PWM (Pulse Width Modulation) controlled stir plate: PWM stir plate design. Building the control logic was a fun project for me since building electronic circuits was a hobby of mine before I got a job in the computer industry. Many years after I build my first stir plate I once again looked into building a stir plate  because needed more stir plates for the yeast starter experiments I’m doing.  I knew I needed better fan speed control than using linear voltage controller since it was really hard to control the fan speed in my old stir plate design. PWM control does work much better but takes a few more parts and soldering skills.

PWM controlled double stir plate

Fermentation Tests for Starter and Air Access Experiments

After I conducted the Access to Air and its Effect on Yeast Growth in Starters experiment I also started fermentation tests with that yeast. The tests were designed to stress the yeast during a high gravity wort fermentation that would show differences in the yeast’s fermentation performance. However, it did not show a clear correlation between the yeast’s access to air during propagation and its fermentation performance. It did however show a difference in final yeast viability which suggests that stressing the yeast with an even higher gravity fermentation could show a correlation between yeast propagation and fermentation performance.

 Methods and Materials

1 day after the yeast propagation was complete the yeast had settled and the supernatant starter beer was decanted leaving behind a lose slurry of yeast. 3 ml of this yeast slurry was taken from each flask and added to amounts of 25 Plato wort (ranging from 276 to 280 g) in pint sized Mason Jars. The wort was unhopped and prepared from dried malt extract and water.  After being boiled for 10 min it was allowed to cool and was then filtered to remove hot break and most cold break.

Yeast was mixed into the wort using a stir plate and initial pitch rate was assessed through cell counts. The jar was then covered with a lid but not closed tightly to allow CO2 to escape. Each jar was shaken vigorously to aerate it. All of the fermentation experiments were weighed on a regular basis to keep track of the fermentation progress. Fermentation happened in a 20 C ambient temperature environment.

After 15 days of fermentation the apparent extract content was assessed using a hydrometer (0.990 – 1.020 range) and thermometer for temperature correction. The total cell count was determined through cell counts and viability was assessed with methylene blue (1 drop of 1% w/w methylene blue to a 5 ml yeast suspension).

Results and Discussion

The following table shows fermentation conditions and statistics that were collected for all 4 fermentations.

Tag A B C D  
yeast prop airlock foil air injected no cover  
initial extract 25 Plato
temperature 20 C
fermentation time 15 days
initial pitch rate 42 49 65 47 B/L
highest fermentation speed* 3.9 6.4 4.5 3.9 Plato/day
final pH 4.76 4.76 4.67 4.67  
final extract 5 4.9 5.1 5.4 Plato
ADF 80.0% 80.4% 79.6% 78.4%  
specific growth 0.19 0.29 0.11 0.14 B/g
final viability (Metylene Blue) 60% 52% 81% 91%  

*fermentation speed was determined from the highest rate of weight loss.

Due to the inconsistent yeast slurry densities initial pitch rate was not sufficiently controlled by pitching measured amounts of yeast slurry. This resulted in pitching rates ranging from 42 through 65 Billion per liter. But these different pitching rates do not show a correlation to either the fermentation speed,  final attenuation or yeast growth.

The attenuation limit of the wort was not assessed but the resulting attenuation levels are fairly close to each other and other experiments with this dried malt extract suggest an attenuation limit of around 80% ADF. Since all yeasts got close to this attenuation limit subsequent experiments should increase the initial extract to 30 Plato to increase yeast stress factors during fermentation. This will make the achieved attenuation level a better indication of the yeast’s ability to cope with these stress factors.

It was expected that the yeast that had the most access to oxygen during propagation, which was C, would show the best fermentation performance. That could not be observed in this experiment. In fact, yeast grown with less access to air (airlock and foil covered), showed better attenuation and fermentation speed.

The fermentation performance was assessed indirectly through a measurement of escaped CO2 based on the loss of weight during fermentation.  Given the rather large outlier for A (air lock covered yeast propagation), which finished with about 1% less weight than the other fermentations while the actual attenuation were fairly similar between all fermentations, these results need to be treated with caution.  If this holds true in subsequent experiments it would be an indication that less aerobically grown yeast (less O2) is better prepared for fermentation and thus does a better job initially than yeast grown more aerobically.

CO2 escape during fermentation plotted as % initial weight loss over time. Fermentation was done in loosely lidded Mason Jars which may have allowed for uneven gas exchange. All 4 samples finished at roughly the same final extract level and larger overall weight loss of “airlock” should be seen as an outlier. Experiments need to be repeated in airlocked fermentation vessels. Note that the labels refer to how the yeast was propagated and not how the test fermentations were conducted.

A stark difference was notable in the viabilities of the yeast sediment. Yeast grown with more access to air (air injected and open) showed significantly more viable cells after 15 days of fermentation and a final alcohol concentration of about 10.5% v/v. This suggests that those yeasts may do better during the late phase of fermentation and that they could have outperformed the differently propagated yeasts  in higher original gravity worts. The most straightforward explanation of the better health is that those yeasts had larger sterol reserves which they shared with their offsprings and which better protected them from the toxic alcohol environment. Methylene Blue is known to overestimate viability and these experiments should be redone with a stain that is known to be more reliable (Trypan Blue) or plate counts.

Final cell culture of wort fermented with yeast propagated in a foil covered flask. Stained with Methylene Blue. Stained blue cells are presumed to be dead cells.

Final cell culture of wort fermented with yeast propagated in a flask open to the air. Stained with Methylene Blue. Stained blue cells are presumed to be dead cells.


Tested viability (Methylene Blue) of the yeast sediment after 15 days fermentation of a 25 Plato unhopped wort. The labels refer to the access to air that the pitched yeast had during propagation.


While this experiment was intended to show fermentation performance differences for yeast grown under different propagation conditions it fell short to do so. A repeat of the experiment is needed for more conclusive data. Despite its shortcomings this experiment resulted in data that yeast grown with more access to air is better able to withstand high alcohol environments than yeast grown with limited air access if the initial population size is about the same.

The results also suggest that yeast grown with less air access, presumably less aerobic growth, ferments faster and may lead to better attenuation. More experimentation is needed to confirm this effect.


Stir speed and yeast growth

I’m starting to hit a stride with respect to yeast growth experiments. Last week I posted data on Access to Air and its Effect on Yeast Growth in Starters, this week I have data on the effect of the stir speed.

Some home brewers believe that as long as the starter is moving there is sufficient opportunity for the head space oxygen to diffuse into the starter beer and become available to the yeast as a nutrient. I never really believed that. Last week’s experiment showed that yeast growth does benefit from increased access to oxygen. So, if yeast growth is a reflection of the amount of oxygen taken up by the starter, then the impact of stir speed on oxygen uptake can be shown by its effect on yeast growth.

The setup of the experiment was simple. About 1200 ml of 8.8 Plato wort were prepared from DME and water. There is nothing magical about 8.8 Plato. That’s just how it came out after evaporation and topping off more water than planned. That wort was inoculated with WY2042, the low flocculant lager yeast that has become my favorite lab rat, to an initial density of 0.11 B/g or 10 B/L. That’s a pretty low initial cell density but I wanted the cell growth to be dominated by the available nutrients and not the health or reserves of the initial yeast population. The yeast was about 2 days old. That means 2 days after having been propagated last.

The inoculated wort was distributed among four 500 ml Erlenmeyer flasks. Not all flasks received the same amount of wort since I wanted to prevent the slow speed one from developing a vortex.  After that the flasks were placed on identical PWM (pulse width modulation) controlled identical stir plates at about 22 C. The stir speed was adjusted to:

  • low: no vortex, but yeast is kept in suspension
  • medium: vortex reaches all the way to the stir bar
  • high: strong vortex and lots of air bubbles are visible in the starter

I also added one experiment where I added one drop of Fermcap S to suppress foam formation. But the stir speed was so high that there was still foam formation even with the Fermcap S. This was also done on a high speed setting. No information about the actual RPMs of the speed settings is available.

All four starters were done uncovered in order to eliminate differences in gas exchange that may have resulted from crimping the aluminum foil differently.

The following are images that illustrate how the starters looked at the beginning:


Slow speed setting. A mere dimple was noticeable on the surface of the starter. Total wort weight was 318 g.

Slow speed setting. A mere dimple was noticeable on the surface of the starter. Total wort weight was 318 g.

Medium speed setting. A vortex was drawn all the way to the stir bar and created some foaming. Initial wort weight was 296 g.

Medium speed setting. A vortex was drawn all the way to the stir bar and created some foaming. Initial wort weight was 296 g.

Fast stir speed: bubbles were constantly drawn into the starter giving it a milky appearance.  Initial wort weight: 256 g

Fast stir speed: bubbles were constantly drawn into the starter giving it a milky appearance. Initial wort weight: 256 g


Fast stir speed + Fermcap S. Same appearance as the “fast stir speed experiment”. Initial wort weight: 263 g

Results and Discussion

This experiment did show a strong correlation between stir speed and yeast growth. The slower the stir speed was the less yeast was grown per initial gram of extract.


This is not surprising given the fact that a well developed vortex allows for a better gas exchange between head space and the starter.  The growth rate of 2.08 B/g for the medium stir speed is in line with the growth rate of 2.25 B/g that the same starter set-up achieved in the Access to Air and its Effect on Yeast Growth in Starters experiment. The measured growth rate for the starter with Fermcap S was slightly lower but should be seen as equal to the other high stir speed starter due to the uncertainty in cell counting.


Stir plate stir speed and resulting vortex development does have an impact on yeast growth. The obvious conclusion is that one should choose a larger flask if that leads to a better vortex. Given that yeast growth depends on the amount of available extract an interesting trade-off becomes apparent: Is it better to have a smaller volume of higher gravity starter with a good vortex or a larger volume of lower gravity starter with a lesser vortex. I’ll be investigating this trade-off soon.


I’m not a fan of foam control agents like Fermcap S in brewing. While it can be argued that it is safe (although the manufacturer recommends removal through filtration) it represents a shortcut that home brewers should not embrace. Especially the ones that are complaining about the shortcuts that large commercial brewers are taking. I’m including it in my research in simply because I want to see if the foam produced by a starter gets in the way of the yeast’s access to oxygen.  In this case it did not make a difference which was likely due to the fact that the starters did not develop much foam to begin with and the vortex was quite strong.

Access to air and its effect on yeast growth in starters

Tonight I was finally able to do cell counts on an experiment that I wanted to do for a while now: “How does the access to air affect yeast growth in starters”. The experiment compared stirred starters capped with airlock, aluminum foil, no cover and injected air.

The setup was very simple. 8.9 Plato wort was prepared using DME and water (no hops) and inoculated with a 2 day old culture of WY2042 (Danish Lager). The innoculation rate was 10.8 B/l or 0.12 B/g (billion cells per gram of extract). The inoculated wort was split between four 500 ml Erlenmeyer flasks. Each flask received about 275 g wort.

All 4 flasks were placed onto identical stir plates set to identical speed in a temperature controlled incubator. The temperature during the experiment was 22 C.

Setup for the yeast growth over "access tro air" experiment

Setup for the yeast growth over “access tro air” experiment

The air injection was done with sterile air and the end of the glass tube was positioned about 5 mm over the wort surface. This was done to avoid foaming and allowed air to be absorbed through the vortex.

All starters were allowed to grow for 2 days. After that time no more CO2 escape was noticeable in the airlock covered starter.

Results and Discussion

The following chart shows the amount of growth as billion new cells per initial gram of extract that grew in each of the starters. The error bars are based on a counting error of 10% that was applied to both the initial and the final cell count. Given the small number of initial cells the error of the final cell count is dominant in this case.

specific growth for each of the starters

specific growth for each of the starters

It is apparent that increased access to air results in more yeast growth. In a previous experiment (not published) that compared an airlock against a foil coveted stirred starter the air lock covered starter showed a growth of 1.0 B/g for the air lock covered starter and 1.8 B/g for the foil covered starter. That result was more dramatic than the difference shown here.

The stream of air injected into one of the starters was so intense that it actually caused significant evaporation. It lead to a weight loss of 20% compared to the 2.2-3.2% for the other starters. Final cell counts considered the actual final volume.

The increased yeast growth could be caused by 2 different mechanisms.

  1. the more air that is available the more aerobic metabolism the yeast is able to perform. That means more energy for growth since aerobic metabolism is able to generate more ATP per mole of glucose than anaerobic metabolism. But in worts with high levels of sugars, as it is the case here, aerobic metabolism is limited by the Crabtree Effect.
  2. yeast growth in wort is limited by available oxygen for sterol production.  That means that access to more O2 allows more cells to be grown.

This experiment is not able to shed light onto this and more experimentation is needed. Since yeast are able to absorb sterols from the growth medium the addition of olive oil to stirred and airlock covered starters could show if sterol synthesis is a limiter to growth in starters.


The better access a starter has to fresh air the more yeast can be grown. More experimentation is needed to better understand the limiters to yeast growth in starters.

While a completely uncovered flask is not practical for yeast propagation in a brewery it was included to show how how much can can be gained by not restricting the gas exchange. For practical yeast propagation a more sanitary alternative would be necessary.


Lactate Taste Threshold Experiment

Last weekend I did a yeast handling presentation to Brew Free Or Die club members and I took the opportunity to conduct a lactate taste threshold experiment with 8 club members. While it had little to do with the topic of the technical session it is a subject where I wanted to do some experimentation for quite some time.

Acidulated malt and 88% lactic acid are very popular acids for mash pH correction but since lactic acid has a rather distinct taste the question that is on many brewer’s minds is: “How much lactic acid is too much“.

Since in most cases lactic acid is only added to counteract water alkalinity and bring the mash pH into the desirable range of 5.3-5.5 it can be assumed that the added lactic acid will not lead to a lower than normal beer pH. In other words, we don’t have to worry about beers that taste sour.  But we do have to worry about the characteristic taste of lactate. Lactate is what’s left when lactic acid gives up its proton to neutralize a base or contribute to pH changes.

The experiment was designed such that the acidity of the lactic acid was neutralized with slaked lime. While that also adds calcium in addition to the lactate it matches brewing reality where highly alkaline waters oftentimes come with high calcium levels. I had the choice between calcium (from slaked lime) or sodium (from sodium hydroxide).  Both calcium lactate and sodium lactate tasted very similar in water which shows that sodium doesn’t necessarily lead to a salty taste. I decided to go with calcium lactate since calcium is generally the dominant cation in alkaline waters.

I was very surprised to see how many of the tasters struggled with identifying the flavor in the 4 sets of samples they were given (water, Bud Light, Budweiser and Sierra Nevada Torpedo Ale). Even levels as high 1200 mg/l, which amounts to a whopping 23% acidulated malt, were not correctly identified by some tasters.  Below is a link to a more formal write-up of the experiment and those interested can go ahead and check my numbers.

Here is a chart that shows for each taster the highest lactate level that was identified as tasting like the control:

highest lactate level that tasted like the control


After having done this experiment and having tasted samples with added lactate myself I think that a safe upper limit of 400 mg/l lactate or 7% acidulated malt is reasonable with the assumption that the mash and beer pH are at acceptable levels. While 7% is higher than the 5% that is currently seen as the safe upper limit for acidulated malt use it should be noted that there might be other benefits to  reducing the amount of minerals in a given water before acidulated malt is used to neutralize the remaining alkalinity.

A formal write-up of the experiment can be found on the braukaiser.com wiki: Lactate Taste Threshold Experiment


This all started when I was preparing one of my presentations for ANHC-3 and I looked into the patent for Boston Beer Company’s Infinium and other patents for high attenuation beers. I found that an enzymatically active malt extract (basically wort with active b-amylase enzymes) can be added to the fermenter. I was skeptical about this approach since malt is full of beer spoilage organisms (which is why you should not handle or mill malt in your fermentation area) and brewers rely on boiling to kill these organisms. However, boiling would also denature all the enzymes. According to the patent I found holding the mash for 30 min at 60 C before pulling the enzyme extract should be enough to kill the microbes but preserve enough b-amylase to be a useful in the fermenter.

So when I had a low fermentability Weissbier I gave this a try in a small test fermentation. Here are the two blog posts on that topic

The result was that I did not spoil the beer and that the enzymes in wort don’t break down as much of the residual sugars, and possibly proteins, as Beano does. Based on these results I was planning to use this technique on a full 18 l batch.

Since I expected close to 100% apparent attenuation it had to be a big beer. High attenuation and thus lighter body works well with a Double IPA. In fact many brewers of good DIPAs use sugar as an adjunct to add alcohol without adding body. So I brewed a stronger version of my KaIPA using this recipe: KaIPA^2 on Brewer’s Friend. It uses lots of my homegrown Cascade hops and hop extract for the bulk of the bittering.

Key was an initial mash rest at 60 C for 30 min and then filtering some of that mash to collect about 500 ml enzymatically active wort. That wort was cooled immediately and used to wake up the yeast. Using it to wake up the yeast was not necessary but why not. That way the yeast could get a head start and I would not forget to add it later.

When diastatic enzymes are used in the fermenter the wort fermentability set during mashing doesn’t matter which is why I raised the mash temp to 70 C after the 60 C rest. That way conversion was faster. The rest of the brewing process was as usual. To check the spoilage potential of the enzyme extract I took two wort samples from the cast out wort. To one of these samples I added the enzyme extract. Both samples were incubated at about 20 C to perform a wort stability test. To my surprise the sample to which I added the enzyme extract showed signs of microbial growth at about the same time as the other sample, which was after 3 days. This means that the enzyme extract did not carry substantial more microbes than the cast-out wort. If you plan to try this technique you may also want to do a wort stability test with and without the enzyme extract.

The fast ferment test for this beer also got some of the enzymatically active wort which is important to get an estimation of the actual attenuation limit of the beer. In this case the FFT stopped at -0.2 Plato which is an attenuation limit slightly above 100%.

To keep the production of higher alcohols in check I started the fermentation at 14 C (58 F) which is fairly low for the used yeast (WLP 001 – American Ale). After a few days I raised the temperature to 16 and then later to 20 C. The production of higher alcohols happens when the yeast consumes wort amino acids and that only happens during the growth phase which is generally over once high Kraeusen has been reached.

8 days after pitching the beer reached 5.0 Plato (down from 19.6 Plato). I let it go for another week in the primary fermenter before I transferred to a keg with some of the yeast. Later, after some more fermentation in the keg, I added gelatin and put the beer on tap. I was a bit lazy with taking more detailed notes.

I have been enjoying this beer for the last 2 weeks. The actual fermentation reached only 2.1Plato (an attenuation of almost 90%) which is higher than I expected based on the fast ferment test and the next time I’ll have to let the beer ferment longer. Unfortunately this IPA wants to be enjoyed young and 30 days after brewing the hop character is starting to fade. I still have the option of dry hopping in the keg which I may want to do.


OE: 19.6 Plato

AE: 2.1 Plato

ADF: 90 %

ADF (limit): 102 %

ABV: 9.6 %

IBU: 54 (Tinseth estimation)

beer pH: 4.30


Tasting notes:

Because of its high attenuation the beer has the mount feel of a Pale Ale but the high alcohol is evident both in aroma and taste. The hop character is fading but I have not added any dry hops yet since I was hoping to be able to rely on the 30 min hop stand with about 40 g of whole flower cascade hops.

Future improvements:

There are a number of things I want to improve in the future. On top of the list is to get the yeast to ferment closer to the attenuation limit. That probably means more yeast, possibly with some O2 during fermentation, and longer primary fermentation time. I think 95% attenuation is a reasonable target. To keep the current mouthfeel of the beer at 95% ADF I want to use a substantial portion of wheat or rye malt in the grist. Wheat malt would provide protein and rye malt would add b-glucans. Neither of these compounds will be attacked by the enzymes and should provide an upper limit for the attenuation.

This experiment was a definite success. The beer is a high gravity beer that is very enjoyable. Any concerns I had about adding non boiled wort to the fermentation were not justified. I also did not produce the dreaded “rocket fuel” that many brewers seem to get when they use enzyme preparations like Beano. I encourage others to give this a try.  Maybe this will become an accepted method of brewing DIPAs that are extremely or even too drinkable for their alcohol content.


A New Mash Chemistry and Brewing Water Calculator

When I started helping Brewer’s Friend as a technical adviser I couldn’t help but notice that the mash pH predicted by its brewing water calculator was way off. Since I have done extensive work on brewing water and mash chemistry already I took this as an opportunity to develop a new Mash Chemistry and Brewing Water Calculator from scratch. The goal was to build something that provides a simple and intuitive user interface yet implements the underlying chemistry to at a level of accuracy that is generally not done in brewing water calculators. In fact the only calculator that goes to that extent is A.J deLange’s NUBWS (Nearly Universal Brewing Water Spreadsheet).

Since Brewer’s Friend is an online recipe calculator the new calculator would also become an online tool. This worked very well in its favor since it is very cumbersome to model complex systems in spreadsheets. PHP, or any other programming language for that matter, makes that type of modeling much easier. In addition to that modern web browser technology makes it simple to create dynamic forms that can readily adjust the form to only asking the user for information that is actually needed based on the context.

That was 3 months ago and after many long nights of coding, re-coding, testing and even running more mash pH experiments version 1.0 has finally been released and is available on Brewer’s Friend.

When you first open the calculator it presents itself like any other basic water with sections for source water, salt additions, grist, mash pH and final water report following this flow chart:

Flow chart for basic use of the calculator

Flow chart for basic use of the calculator

But that’s not all. For those who need want to do more complex water treatment calculations, the full flow chart looks more like this:

Full flow chart for brewing water and mash chemistry calculator.

Full flow chart for brewing water and mash chemistry calculator.

All these additional section are hidden by default and can be shown on demand.



The first release features makes these features available:

  • Blending of two water sources
  • Bicarbonate/carbonate content can be set from either alkalinity or bicarbonate. pH can also be entered for increased accuracy
  • Electrical balance (ion balance) of the source water
  • Simple GH&KH measurements can be used as a crude way of specifying the source water.
  • Report of basic and advanced water parameters of the source water. Among the advanced properties are temporary/permanent hardness and CO2 partial pressure
  • supports all major salts (including magnesium chloride) as well as the hydroxides slaked lime and lye
  • Alkalinity reduction through boiling and slaked lime. These are features that rely on a more accurate implementation of the water’s carbo system
  • Wide range of supported acids including the less commonly used citric, tartaric and acetic acid.
  • Salt and acid additions can be made to all water or only the strike (mash) water
  • A different water source can be used for sparge water. In most cases that might be reverse osmosis water when the tap water is suitable for mashing.
  • Salt additions to sparge water or kettle
  • Sparge water acidification with a wide range of acids.
  • Detailed report of the treated mash water
  • Support for undissolved chalk.
  • Grist pH properties can be estimated from beer color or malt bill
  • Mash pH prediction based on balancing the various weak and strong acid systems that might be present (carbo system, weak acids and grist)
  • overall water report based on the mash and sparge water profile
  • target water comparison of the overall water report

For now this tool is only available as a stand-alone calculator but Brewer’s Friend is planning to integrate it into the recipe editor. This will eliminate duplicate entry of the beer’s malt bill. It will also allow the user to use saved source water profile(s).

Go ahead and give it a try. If you have feedback, positive or negative, please let me know:

Mash Chemistry and Brewing Water Calculator

In subsequent posts I’m planning to write more about some of the discoveries I made while writing this tool and how it’s mash pH prediction does compared to actual mash pH data that I have.