My Brewing Log

This is a blog entry I have been thinking about a while. How precise is the ppg (points per pound and gallon) based efficiency calculation really. The reader should see this as something that is interesting to know and more of an exercise in using Plato and sg rather than something that any brewer needs to worry about

When calcylating efficiency (American) home brewers usually use:

(1) Eff = 100 * (gravity points of wort * wort volume) / (grain weight * grain extract potential)

Wort volume is given in gallon, grain weight in pound and extract potential in ppg. But that's not how efficiency is actually defined. It is defined as the ratio between the extract weight in the kettle vs. the extract potential of the grain:

(2) Eff = 100 * extract weight in kettle / grain extract potential

The grain extract potential is simple. It is its weight multiplied with the extract content determined in the laboratory mash. For most base malts it is about 77% (80% dry basis extract and 4% moisture content). Going forward I will call the grains extract potential "e". The weight of the extract in the kettle is a bit more complicated. For that we have to look at the Plato scale. Many brewers know degree Plato as another way of expressing wort strength. To be exact: the wort strength in Plato is the ratio between the weight of the extract dissolved in the wort and the the total wort weight:

(3) P = 100 * extract weight in kettle / wort weight in kettle

Extract weight in kettle is what we need for (2) but I still need the wort weight weight in the kettle. For that I simply remember that sg (specific gravity) is nothing else than the density of the wort in kg/l. It follows that the wort weight in kg is the product of wort volume in l and its specific gravity:

(4) extract weight in kettle = sg * wort volume in kettle

Now I can calculate the actual efficiency by using (2), (3) and (4). First some clean-up and shorter notatons for the variables:

• Eff_ppg = Efficiency calculated using gravity points and ppg for extract potential
• Eff_% = Efficiency calculated using Plato and extract % for grain extract potential
• P = wort strength in Plato
  
• sg = wort strength in specific gravity (1.xxxx)
  
• GP = wort gravity points ( = (sg - 1)*1000)
  
• V_l = wort volume in liter
  
• V_gal = wort volume in galon
  
• m_kg = grain weight in kg
  
• m_lb = grain weight in lb
  
• e_% = extract potential of the grain in %
  
• e_ppg = extract potential of the grain in ppg

With that the two efficiencies are:

(5) E_ppg = 100 * GP * V_gal / (m_lb * e_ppg)

(6) E_% = 100 * sg * P * V_l / (m_kg * e_%)

Grain lab analysis results don't show the extract as ppg but as percent of dry weight. To get the ppg equivalent I need to find a formula that calculates e_ppg from e_%. Since it is assumed that both efficicncy calculations (5) and (6) are equal I can set them equal:

(7) E_ppg = E_%

Now the busy work. They both use weight and volumes but in different units. That will be fixed by assuming these conversions:

(8) V_l = V_gal * 3.78
(9) m_kg = m_lb * 0.45

For simplicity I'll be using the simplified Plato to sg conversion. I'll later discuss how much that makes a difference.

(10) P = GP / 4 = (sg - 1) * 250

After putting all this into (5) and (6) I end up with this huge equation:

(11) 100 * (sg - 1) * 1000 * V_gal / (m_lb * e_ppg) = 100 * sg * (sg - 1) * 250 * V_gal * 3.78 / (m_lb * 0.45 * e_%)

Luckily this can be cleaned up considerably. V_gal and m_lb exist on both sides and fall out. So does (sg-1). All the constants can be consolidated into one. What's left is this:

(12) 0.476 / e_ppg = sg / e_%

solving this for e_ppg gives:

(13) e_ppg = 0.476 * e_% / s_g

This equation means that the extract potential in ppg depends on the grains extract potential in %, which is to be expected, and the specific gravity of the wort for which efficicncy is calculated. This was not expected. Here are a few examples. If sugar, which has an extract potential of 100%, is used to make a 1.040 sg wort it has an extract potetial of ~ 46 ppg. If it was used to make a 1.080 sg wort it has an extract potential of only ~ 44 ppg

The same is true for a base malt with 80% dry basis extract and 4% moisture. The actual extract content is 76.8%. If used for 1.040 wort its ppg extract potential is ~36.0 ppg. When used for 1.080 wort the extract potential is ~34.6 ppg.

As a final exercise lets look at a chart that plots the two efficies over the gravity of the wort. The wort volume is held constant while the grain bill is scaled such that the "%" based efficiency remains constant. In addition to that, the sg to Plato conversion is done using the officicial ASBC conversion formula which is a polynominal fit of their sg to Plato tables [deLange]:

(14) P = -616.868 + 1111.14 * sg - 630.272 * sg^2 + 135.997 * sg^3

While there are many similar formulas out there, this is the official one given by the ASBC (American Society of Brewing Chemists) and it should be seen as the standard.

This is the chart I came up with



It plots 3 curves. "Eff_% using the exact sg to Plato conversion" uses (14) to convert between sg and Plato. It is constant at 70% because this formula is used to calculate the necessary grain weight for the given volume and specific gravity. "Eff_% using the simple sg to Plato conversion" uses (10) to calculate the sugar content (Plato) from the specific gravity. "Eff_ppg" calculates the efficiency using gravity points and an extract potential of 35.7 ppg.

Despite the existing discrepanacy and incorrectness of the ppg based efficiency calculation, which I discussed earlier in this text, it tracks very well with the actual efficiency of 70% over a wide range of specific gravities. The reson for this is simple: while I showed that technically the extract potential in ppg also depends on the specific gravity, I also simplified the sg to Plato conversion by using (10) instead of (14). Both errors compensate each other to some extend. This also becomes clear when looking at the efficiency which is calculated using the simple sg to Plato conversion. It already shows an error of ~4 percent point at a specific gravity of 1.100.

Conclusions

Does it really matter in brewing whether you use the ppg based forumla or the Plato based one? Not really. If you always use the same formula for efficiency calculation and subsequent recipe design it doesn't matter at all. It may matter when discussing and comparing efficiency with other brewers. In this case the ppg based approach is within 1% of the actual efficiency for all realistic gravities. That error, however, is too small to be a conern in home brewing. Using the % based efficiency calculation with a crude sg to Plato conversion, on the other hand, can overestimate efficiency significantly. Thus care needs to be taken when converting Plato or Brix readings into specific gravity readings. That is in particular true for high gravity worts.

One last word about ppg or "points per pound and gallon". It should be called "point gallons per pound" or pgp since it is an expression of how many "point gallons" (gravity points multiplied with gallons) one can get from one pound of grain, sugar, etc. Its actual unit is gal/lb. 

[deLange] A.J. deLange: Specific Gravity Measurement Methods and Applications in Brewing.

This was the first time that I compared dissolved chalk against undissolved chalk in a 5-gal "production" batch of beer. Up to this point I have only done small scale experiments. Those experiments suggested that chalk dissolved with CO2 would be twice as potent in raising the mash pH as undissolved chalk is. As a result I new that I should cut the amount of chalk needed in half when it will be dissolved with CO2.

To brew the Schwarzbier I used the following grist. This is my standard recipe for a Schwarzbier:

• 53% Pilsner malt

• 40% Munich Type II malt

• 4% CaraMunich III malt

• 3% Carafa I special

The water was prepared from reverse osmosis water by adding the following salts. Version A uses undissolved (i.e. suspended chalk) while version B used dissolved chalk

The resulting profile was calculated as follows. Note that I do have an old analysis of the reverse osmosis water which I included in the calculated mineral profile:

*) There is some ambiguity as to how much calcium is actually contributed by undissololved chalk since it contributes only half its alkalinity potential, it may also contribute only half its calcium. These results assume that the chalk contributed all its calcium. The result is a lower residual alkalinity compared to the water with only half the chalk but dissolved.

The salts were then weighed. For beer A, they were mixed into the strike and sparge water. Since the chalk was not dissolved the water remained cloudy. Water treatment for the strike water was done in the mash kettle.

For beer A the salts were added to 2 liter soda bottles and reverse osmosis water was added. Then the bottles were carbonated with a carbonator cap. Once sufficiently carbonated the water cleared overnight which was a sign that the chalk got dissolved. This water was then added to the remaining reverse osmosis water for mashing and sparging. The mash water was prepared the night before to allow residual CO2 to escape. No chalk precipitated during that time, There was also no precipitation of chalk during the heating of the strike water or the sparge water.

The resulting pH values during the brewing process are shown in the following table. All pH values were measured with a sample cooled or heated to 25 C

For both beers the pH dropped during mashing which I contribute to the continued release of acidic compounds from the dark specialty malts. One oddity is that for batch A, which used undissolved chalk, the kettle full pH is lower than the cast out pH. Generally the pH falls during boiling. This is something worth paying attention to in future batches although it may also have been a measurement error. The initial mash pH of batch B is greater, which supports the fact that the residual alkalinity of its water should have been higher. This is the case if all the calcium added by the chalk is considered for undissolved chalk as it was done in the aforementioned water analysis.

I have not yet done a final tasting with these two beers. But preliminary tasting of both batches during their fermentation and conditioning did not show any significant differences

Conclusion:

To achieve roughly the same mash pH, only half the chalk is needed when it is dissolved with CO2.

After last year's Maibock, this is the 2^nd experiment where I compared a beer brewed with decoction mashing and a beer brewed with infusion mashing.

This time I wanted to see if there is a more pronounced flavor difference if the majority of the grist was composed of highly kilned base malts. This is one type of grist for which decoction mashing is still fairly common in Germany. test test test . So I chose a basic Dunkel recipe and the brewing process is outlined after the mash diagram for the 2 beers (click the diagram for a larger version).

It should be noted that the Dark Munich malt caught me by surprise and the mash for Dunkel II resulted in a rather unfermentable wort (attenuation limit 71%) which was compensated for during the mash of Dunkel III (see longer maltose rest). As a result the wort for Dunkel III was more fermentable. But both beers finished with a similar attenuation (67% and 69%). The poor fermentability was attibuted to the enzymatic weakness of the Best Malz Dark Munich which took a long time to convert (see the 40 min 70C rest of the decoction) and showed similar attenuation problems in subsequent beers.

3 ½ months after brewing Dunkel II and 3 months after brewing Dunkel III I tasted the beers side-by-side. It should be noted that at the time of this tasting I was not aware that I brewed one with decoction and the other one without. I had brewed quite a number of other beers in between and actually forgot how I mashed these beers and thought that they were both brewed with decoction until I checked my notes.

As you can see I did notice differences berween the beers but it is difficult to tie them to the decoction alone. I contribute the better clarity, lower head retention and thinner mouthfeel of the more intensely mashed Dunkel III to the stronger protoelytic activity in the mash. Its increased sweetness stems from the larger amount of residual fermentable sugars (see attenuation delta) compared to Dunkel II. I even considered Dunkel II (the non-decocted, more precisely only 3 min thin decoction boil) to be the more malty of the two beers.

Conclusion: This experiment was not as conclusive as the Maibock experiment and I would even call it inconclusive. There were too many differences between the analytic parameters (in particular the attenuation numbers) of the two beers to tie their slight taste differences to the more intensive mashing (including a 35 min decoction boil) of the Dunkel III. A future experiment needs to increase the decoction boil time to 60 min and attempt to keep the original extract, attenuation limit and attenuation and fermentation the same.

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When reading up on brewing Weissbier (also known as Bavarian Wheat) one of the suggestions is a ferulic acid rest. This rest around 43 C (110 F) works best at a pH > 5.7 and liberates ferulic acid into the wort. This ferulic acid is the precursor to 4-Vinyl-Guajakol which is responsible for the the clove flavor produced by Weissbier yeats. The more ferulic acid there is in the wort the more 4VG should be produced by the yeast and the more clove character the beer should have.

This is what I wanted to test. So I brewed a Weissbier recipe twice. Once with a simple Hochkurz mash and another one with an additional 30 min 43C rest at a pH > 5.70. For the second beer acid malt was added at 61C. This is above the optimal range for protoelytic activitry since I also wanted to limit the protein degradation during the time the mash spent in the 45-55C range.

The following table lists the process steps taken for the 2 beers:

Note that the fermentation for the 2nd batch slowed down signficantly after it reached a gravity of 6 Plato. At this point I decided to pitch a lager yeast and I cooled the beer for the time it took to propagate that yeast. This was to drop out most of the original yeat and limit autolysis. This was unplanned and I hope it is not the reason why the results of the experiment are like they are.

Tonight I tasted the two beers:

Conclusion: For the chosen yeast holding the ferulic acid rest didn't make any noticeable difference in the clove flavor that was produced during fermentation. While additional experiments should be made to confirm these findings it is very much possible that this rest is not worth the additional work.

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This is an experiment that I wanted to try for a while: Sparge a mash with cold instead of hot water.

Based on my understanding of the lauter process sparging with cold water should have no or only little impact on the efficiency if all the sugars, that will be dissolved, are dissolved during the mashing process. While a colder sparge could slow the speed of the run-off by causing the wort to be more viscous and flocks of coagulated protein be smaller it should not affect how many sugars are left behind. Especially in batch sparging where there is no concern about channeling through the grain bed.

I decided to give the cold water sparge a try on one of my Schwarzbier recipes. But since I also wanted to change the grain bill slightly it is not a true side-by-side where only the temperature of the sparge water changed. Here is what I did for the two beers:

The things to note is that the conversion efficiency was very high on both batches. Almost all of the extract potential was realized in the mash which is an indication for good and complete mashing. The lauter efficiencies (percentage of dissolved extract that made it into the kettle) for both beers were very similar and as a result the efficiencies in the kettle were very similar as well. The differences that can be seen are easily within measurement errors.

This shows that a cold water sparge does not necessarily lower your efficiency. 

It should also be noted that the 2nd runnings, which were the cold runnings, never cleared up. The remained hazy throughout the sparge. 

Tonight I tasted the beers. Here are pictures that show the color and clarity of the beer

And the taste notes:

The cold sparged beer is definitely a slightly more hazy than the hot sparged version. This may actually have been the result of the cold sparge although I don't have a solid explanation for this. If the haze results from an increased protein content it may also explain the slightly better head retention and fuller mouthfeel.

Conclusions:

• Cold sparging does not have strong adverse effects on efficiency and beer quality
• when a mash-out is performed it has no apparent effect on the fermentability of the wort. I don't know if this is still the case when no mash-out is done.
• it may make the beer more prone to haze
• it does not really save time since the wort at the end of the lauter will be colder and require more time to be heated to boiling temperatures
• it can save the need for a pot for heating the sparge water
• Since the spent grain temperature is lower at the end of a cold sparge less energy is wasted.

While this was an interesting experiment I don't plan to repeat it in the near future. At this point I don't see any benefit in this practice except for cases were I forget to heat the sparge water.

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A few weeks back I decided to write another brewing water calculation spread sheet. The formulas were mostly taken from the literature and existing spread sheets. Then I decided to add a cation (positively charged ions) to anion (negatively charged ions) balance check just to see if the water profile that I created made sense. This is when I noticed an imbalance when creating brewing water from scratch by using distilled water and salts. The resulting water should not show an imbalance and every cation should have matching anion. But it was showing an imbalance when chalk was used. So I gave the fomulas used for chalk a closer look.

 And found that 1 mol (a unit that is proportional to the amount of molecules/ions of a particular substance) of CaCO3 was assumed to add one mol of bicarbonate to the water. And that in most spreadsheets and calculators the bicarbonate contribution was later used to calculate the alkalinity as CaCO3. But that didn't seem right. If CaCO3 adds only one bicarbonate, it also needs to add one hydroxyl ion (OH-):

(1)  CaCO3 + H20 -> Ca2+ + HCO3- + OH-

Since this would liberate hydroxyl the pH of the water would need to rise. If that is not happening then chalk can also be dissolved in the presence of CO2

(2)   CaCO3 + H2O + CO2 -> Ca2+ + HCO3- + HCO3-

In this case each mol of chalk would add 2 moles of bicarbonate. Yet another reaction is possible in the presence of acid and free protons

(3)  CaCO3 + H+ -> Ca2+ + HCO-

(4)  HCO- + H+ -> H2O + CO2

If neither of these reactions hapen the chalk won't dissolve. And that is clearly happening in brewing: If you add chalk to the brewing water it just turns the water cloudy and it will eventually settle. 

But does it really matter if the chalk dissolves or not? No. Because the bigger picture is that we added the chalk to give the water+chalk mixture more "alkalinity" I.e. acid buffering capacity. That acid buffering capacity is needed to reach a targeted mash pH once the malt, and with it acid buffers, has been added. At that point reactions (3) and (4) can take place. Whichever reaction is happening (1)..(4), chalk can neutralize 2 equivalents of acid and for all intents and purposes 1 ppm of chalk should therefore raise the alkalinity by 1 ppm as CaCO3. 

But that is not what most water treatment spreadsheets assume. They assume that 1 mmol/l CaCO3 adds 1 mmol/l HCO3- (bicarbonate) which drops one negative charge on the floor and caused the imbalance that I noticed. And then they go ahead and convert the ppm HCO3- to alkalinity as ppm CaCO3 by multiplying with the factor 50/60. In the end the addition of 1 ppm CaCO3 raises the alkalinity by only 0.5 ppm as CaCO3. This certainly seems wrong and I thought I had it all figured out until I decided to confirm this theory with an experiment.

The experiment is seemingly simple. Make small mashes with 3 different waters that are supposed to have the same residual alkalinity and test their pH. The first water (A) would be reverse osmosis water and serve as the control. The second water (B) would be reverse osmosis water with chalk and calcium chloride added such that the added residual alkalinity is 0 if the chalk contributes 2 alkalinity equivalents. The 3rd water (C) has chalk and calcium chloride added such that the added residual alkalinity is 0 if chalk contributes only one alkalinity equivalent. Whichever water that causes a mash pH to match the RO water mash pH the closest would have used the correct formula for alkalinity contributions by chalk. Here is a summary of the waters used:

• water A: reverse osmosis tap water
• water B: RO water + 80 ppm CaCO3 + 290 ppm CaCl2*2H2O; this increases the Ca2+ content by ~110 ppm
  • if 1ppm CaCO3 adds 1 ppm alkalinity as CaCO3 then the water's residual alkalinity (RA) increases by 0.0 over the RO water's RA
  • if 1 ppm CaCO3 adds 0.5 ppm alkalinity as CaCO3 then the water's RA decreases by 2.2 dH (German Hardness) or 40 ppm as CaCO3
• water C: RO water + 150 ppm CaCO3 + 150 ppm CaCl2*2H2O; this increases the Ca2+ content by ~110 ppm
  • if 1ppm CaCO3 adds 1 ppm alkalinity as CaCO3 then the water's residual alkalinity (RA) decreases by ~4.4 dH or 80 ppm as CaCO3
    
  • if 1 ppm CaCO3 adds 0.5 ppm alkalinity as CaCO3 then the water's RA remains unchanged compared to the RO water

200ml of each water were taken and heated to ~64C in the microwave. Then 50g of crushed pilsner malt were added to each water sample and stirred in. The mashes were occasionally stirred and a 15ml sample was taken from each mash after 5 min and cooled to 22C when it was measured with a pH meter. The results were surprising:

• mash A : pH = 5.76
• mash B : pH = 5.69
• mash C : pH = 5.77

According to these results the chalk added only 0.5 ppm alkalinity as CaCO3. And the pH shift for mash B is even in the range that would have been expected from the 2.2 dH RA drop. According to Kolbach the shift is 0.03 pH units for each dH which would be 0.066 and the results show ~0.07.

I couldn't believe it and started to ponder why that would be the case. Why is the added CaCO3 only neutralizing 1 equivalent of acid and not 2? Maybe it has something to do with the chalk not being dissolved.

So I conducted another similar experiment. This time between a control, water with suspended chalk and water with dissolved chalk. The chalk would be dissolved with CO2 which is brought into solution through shaking. Here is what I did. I added 0.24 g chalk and 0.88g calcium chloride to 1.5 l of reverse osmosis water. This is twice the salts added to water B in the previous experiment because I wanted to pronounce the effect of the residual alkalinity difference. I then shook this water and the added salts in a 2l soda bottle until the calcium chloride was dissolved. Immediately after shaking, without giving the chalk a chance to settle, I poured off 200ml for sample B. I then removed another 300ml in order to increase the head space. This headspace was then filled with CO2 and the bottle closed. When I started shaking the bottle, it immediately contracted which was a sign of the CO2 going into solution. After some shaking I let the bottle sit until the water became crystal clear again. This was not the result of the chalk settling but it being dissolved in the water. I then took 200ml of that water for samle C:

• water A: reverse osmosis
• water B: RO + 160 ppm CaCO3 + 580 ppm CaCl2*2H2O
  • RA = -4.4 dH or 80 ppm alkalinity as CaCO3 if chalk adds 1 alkalinity equivalent
  • RA = 0 dH or 0 ppm alkalinity as CaCO3 if chalk adds 2 alkalinity equivalents
• water C: water B + CO2
  • RA = -4.4 dH or 80 ppm alkalinity as CaCO3 if chalk adds 1 alkalinity equivalent
  • RA = 0 dH or 0 ppm alkalinity as CaCO3 if chalk adds 2 alkalinity equivalents

I then heated both samples to 68C, added 50g crushed pilsner malt to each and rested (with occasional stirring) them for 10 min. After that I took 15 ml samples and cooled them to 20-21C:

• mash A : pH = 5.67
• mash B : pH = 5.47
• mash C : pH = 5.66

So it appears that dissolving the chalk in the mash water changes its alkalinity potential. undissolved chalk has less alkalinity potential than dissolved chalk since mash B showed a much lower mash pH which could only have been the result of a lower RA than the 2 other mashes.

But why is this? Does not all the chalk dissolve in the mash as commonly assumed? And if yes why is that? And would it always be 50%? Shouldn't there be enough acid for this to happen via reactions (3) and (4)?

For now I don't have an answer to this. 

This weekend I took the time to take extensive extract and volume measurements during a 2 sparge batch sparging process here is the data and an analysis of that data:

• grist weight 5.6 kg
• total laboratory extract of that grist is  80% of 5.6 kg -> 4.5 kg
• water added to mash: 15.5 l (cold)
• extract of the first running in the kettle 22.5% (% extract is equal to Plato)
• volume of the first runnings in the kettle 9.75l at 65C -> 9.6l (cold)
• extract of the 2nd runnings: 11.75%
• volume in kettle after 2nd running: 20l at 75C -> 19.6l (cold)
• extract of the 3rd runnings: 7.4%
• volume in kettle after 3rd running (pre-boil volume): 26l at 90C -> 25l (cold)
• extract in kettle after 3rd running (pre-boil extract): 14.6%

The first analysis was for the extraction efficiency of the mash. The definition of extract percentages is:

(1)  E = 100% * m_extract / ( m_water + m_extract)

If we want to know how much extract exist in a given wort of known extract content that has been created with a known  amount of water we can do this by rearanging (1) to

(2) m_extract = (m_water * E / 100%) / (1 - E / 100%)

(3) m_extract = (15.5kg * 0.225) / (1 - 0.225) = 4.5 kg

This means that all of the extract available in the grain has been extracted in the mash (100% extraction efficiency). This was confirmed by a negative iodine test of the wort and the spent grain. I.e. no native starch was left.

Since batch sparging was used, a simple model can be used to calculate the lauter efficiency. lauter efficiency * extraction efficiency is the brewhouse efficiency.  For that model we need the amount of wort that is held back in the lauter tun after each run-off. But this is not simply the amount of water used for the mash minus the amount of first wort collected because the volume of the wort increases when the extract is dissolved. To get that volume we can use this formula which is the weight of extract dissolved in a given volume of known gravity wort:

 (4) m_extract = ( E / 100% ) * SG * V_wort

SG is the specific gravity and it will be estimated with 1+E*0.004.Rearranged to V_wort we get

(5) V_wort = m_extract /  ((E/100%) * SG)

(6) V_wort = 4.5 kg / (0.225 * 1.090) = 18.3 l

This means the 15.5 l water and 4.5 kg extract from the 5.6 kg grain made 18.3 l of 22.5% wort. 9.6l of that wort were collected after the first run-off which indicates that 8.7 l are held back in the mash.

Batch sparing is a process of successive dilution of the wort remaining in the grain and running it off. This can be modeled mathematically and has bee analyzed here. But since not all run-offs were of equal size, lets just calculate the efficiency step by step:

The first run-off will extract this percentage of the extract from the mash:

(7) Eff_1st = v_1st_runoff / (v_1st_runoff + v_wort_in_grain)

(8) Eff_1st = 9.6l / (9.6l + 8.7l) = 0.52 = 52 %

If 52% were recovered by the 1st run-off, then 48% of the extract are still in the lauter tun. This extract is dilluted by the sparge water and run off. The volume of the 2nd run_off is 19.6l - 9.6l = 10l and the efficiency of that run-off is:

(9) Eff_2nd = v_2nd_run_off / (v_2nd_run_off + v_wort_in_grain)

(10) Eff_2nd = 10l / (10l + 8.7l) =0.53 = 53%

Using this and the fact that the 2nd run-off was only able to draw from 48% of the extract we can determine the combined efficiency from the 1st and 2nd run off as:

(11) Eff_1st_and_2nd = 52% + 48% * 53% = 78 %

78% of the extract are now in the boil kettle. This leaves 22% in the lauter tun. With a 3rd run off size of 5.4 l we find the efficiency of that run-off as

(12) Eff_3rd = 5.4 / (5.4 + 8.7) = 0.38 = 38%

and the combined efficiency of all 3 run-offs as:

(13) Eff_1st_2nd_3rd =  52% + 48% * 53% + 22% * 38% = 0.86 = 86%

This means that with the given run-off sizes, number of sparges and amount of wort left in the grain, an a lauter efficiency of 86% is to be expected.

The actual efficiency into the boiler is the following:

(14) Eff_kettle = V_kettle * E * SG / (m_grain * 0.8)

the 0.8 represents the 80% laboratory extract of the grain.

(15) Eff_kettle = 25l * 0.146 * 1.058 l/kg / (5.6 kg * 0.8) = 86%

Since the Efficiency is the product of extraction efficiency and lauter efficiency and the extraction efficiency was determined to be 100%, the actual lauter efficiency must have been 86%, which matches the theoretical result very well. As a result no efficiency was lost due to process inefficiencies and to increase that efficiency the following process parameters could be changed:

• more sparge water: this would lead to a larger pre boil volume and longer or stonger boils and may not be desired
• less wort kept in the grain: This mash was done with conditioned malt which makes for a"fluffier" mash. Such a mash may hold more wort and I wonder if an unconditioned mash may result in less wort being held back and thus increasing the efficiency
• equalize the run-offs: the boost expected from that is very low. Se here.
• fly sparging: this method follows a different principle and should yield better efficiencies when done properly. But in addition to more time, it also needs a better lautertun which I don't have.

This experiment was designed to evaluate different Weissbier yeasts. The following yeasts were used:

• 351-1 (This yeast came from a WLP351 vial, but I think it is not the WLP351 strain anymore)
• WY3068 - Supposedly the W68 strain from yeast bank Weihenstephan. A very popular strain among German brewers
• WY3333
• WY3056 - Initially a blend of yeast, but I cultured this one from a single cell colony

The wort was a simple Helles Weissbier wort:

• 70% Weyermann light wheat, 30% Weyermann Bohemian Pils
  
• Step mash (55 C for 30 min -> infusion of boiling water -> 65 C for 45 min -> thin decoction boiled for 10 min -> 72C mash-out)
• 3.7g 10% Target and 7.5g 8% Northern Brewer hops boiled for 60 min
  
• Boiled for 60 min in a 2 stage boil: 1st stage just a simmer, 2nd stage with a 12 %/hr boil-off. I wanted to see if that type of boil, which is done by many commercial brewers, actually works for avoiding DMS. No noticable DMS was later found in the beer
• Cast-out wort: 16l @ 11.5 Plato
  

 4 one galon glass jugs were filled with 3l wort each. They were oxygenated with pure O2, but I did not take ones on how long (30s are likely). The following amounts of yeast were pitched

• 351-1: 10 ml sediment, propagated from an agar culture
• WY3068: 50 ml loose sediment from a Wyeast activator pack
• WY3333: 35 ml thin slurry from a Wyeast activator pack
• WY3056: 10 ml sediment propagated from an agar culture

It was noted that the pitching rates were rather different, but time and availability didn't allow for all yeasts to be grown the same way to the same amounts.

The yeast was pitched at 18C and since all growlers sat in the same water bath, it was assumed that they would have the same temperature. The temperature measured is the temperature of that water bath and because of the good heat conductivity the actual fermentation temperature was not expected to be different.

Over the next 2 days the temperature rose to 21C (70F) before it fell down to 20 C. The 2nd day after pitching the following extract values were measured:

• 351-1: 7 Plato
• WY3068: 6.5 Plato
• WY3333: 6.5 Plato
• WY3056: 6.0 Plato

Alongside the primary Fermentation, a number of fast ferment tests were done:

• dry bread yeast (1/4 tsp to 150 ml) : 2.5 Plato
• dry bread yeast (1/2 tst to 150 ml) : 2.5 Plato
• WY3056 : 2.5 Plato
• WY3333 : 2.6 Plato

The beers were bottles with residual extract. This means that the beer was simply filled into bottles once the extract level reached 3.7 - 3.8 Plato, which leaves enough residual fermentable extract to properly carbonate the beers. A practice called Gruenschlauchen in German Brewing.

During bottling a strong banana aroma was noticed for WY3056 and WY3333.

After one month (I didn't get to it earlier) the 4 beers were tasted together:

WY3086:

The beer pours a very strong head and is well carbonated. It's aroma shows moderately yeasty notes with some sulfur. The taste shows a little of the Weissbier clove spiciness but hardly any banana even though the beer smelled like banana juice at bottling time. The final extract was 2.7 Plato.

WY3333:

The beer is highly carbonated. It's aroma is yeasty with some banana/bubble gum character. But that fruit was very strong and came out later when the head subsided. The taste shows a restraint spiciness but no fruit. It is also a little yeasty, but more in a good way. Final extract 2.7 Plato. 

351-1:

The beer was not as well carbonated as the others and didn't pour a strong head. This is odd since this yeast is actually able to ferment below the 2.6 Plato of the other beers and was bottled with at the same extract level as the other beers. As a result more fermentable sugars must have been fermented that should have resulted in more CO2. The aroma spots some solvent notes (ethyl acetate). Later, the aroma is more clove dominated. It's taste is more spicy than all the other ones with less yeasty character. Final extract 1.6 Plato (!!)

WY3056:

The beer is highly carbonated. The aroma is clean initially, but once the head fell it showed a slight yeasty character. The taste is bready-yeasty (in a good way) without any signigficant spiciness. This character might make this yeast ideal for a Dunkles Weissbier. Final extract 2.8 Plato.

This was my first attempt on a Gose, a German sour beer that is brewed with coriander and salt. Because I generally don't like sour beers, I only made a 1 gal batch which turned out to be a good idea.

The wort was taken from a batch of wheat beer that was brewed with 70% light wheat malt and 30% Pilsner malt (at 12 Plato) and hopped to about 10 IBU. 0.8 l of the unhopped wort was boiled for 15 min and inoculated with about 1 Tsp crushed malt. This wort was then left to sour at ~ 21 c (70 f) for a few days before 0.5 l were added to 2.5 l of hopped wort and then boiled for 15 min. The boil served to kill all the bugs in the soured wort. 12 crushed coriander seeds and 1/2 tsp of kosher salt were added to the boil as well as 0.5l water to compensate evaporation.

 After cooling the wort was fermented with WY1007 (German Ale) for a week at about 20C (68F) and bottled straight from the fermenter. 2g of table sugar was added to each bottle for carbonation.

 After 2 weeks I tasted the result:

 Appearance:

• good head retention
• cloudy as I remember a Gose from Germany

Aroma:

• there is some light sour aroma, but I think that there should be more

Taste:

• To much salt. The salt is way to prominent and it tastes like Gatorade
  
• Not sour enough. The sourness is rather restrained. I either want to increase the portion of soured wort or just invest into a lacto culture instead of souring with malt
• The coriander is there but barely noticeable. I won't change that for now
• The carbonation was a little low. Most likely it didn't ferment as far as I wanted it to ferment

All in all, a decent, yet not really drinkable first attempt. I'll stick with the small batches off Weissbier batches until I figured out how to get it just right.

This is now the first Weissbier that is part of the "Summer of Wheats":

• 70% Light Wheat malt
  
• 30% Pilsner malt
• 2% acid malt
• 2% CaraAroma

 It was mashed with a Hochkurz mash:

• Infusion to Maltose: 30 mit at 63C
• Infusion to Dextrinizaton: 60 min at 70C
• Decoction to mash-out: 10 min at 76C

Boiled for 60 min with 0.4g/l of alpha acid (Hallertauer) and  fermented a 20C with WY3056.

While I was very excited by a similar beer that I made last year with the same yeast, I'm less impressed with this one. Even though it was fermented fairly high (20 C), the aroma lacks the typical banana esters. One of the reasons might be that the WY 3056 is a blend of yeasts and I cultured the yeast pitch from a slant of that yeast. Most likely the more neutral yeast of the blend prevailed. 

There is also little in the way of spice/clove aroma and taste. But this is dependent on the yeast as well and I didn't do a ferulic acid rest either. Instead I'm getting a mild yeasty note from the aroma and finish. Though there is certainly a "yeasty" category of Weissbiers, I'm not to fond of them.

The 2% CaraAroma made this beer darker than I wanted it to be.

Stats:

• Original Extract: 11.5 Plato
• Fast Ferment Test: 2.7 Plato
• Limit of Attenuation: 76.5 %
• Final Extract of beer: 3.0 Plato
• Attenuation of beer: 74 %

 The limit of attenuation and attenuation of the beer is not quite where I want to have it either. I'd like the fast ferment test extract to be closer to 2.5 Plato and the actual beer extract to be very close to that (2.5 - 2.6 Plato). Weissbiers are generally very well attenuated beers, which is partly a result of the poorly flocculating yeast. This one is a little on the sweet side due to the larger difference between its attenuation and the limit of attenuation.

This beer was an experiment in which I tried a lot of new techniques that I generally don't use in my brewing process. The motivation was that I was not quite happy with the aroma and finish of my beers. For the lagers, in which I use only bittering hops or only little amounts of flavoring hops, I didn't get much aroma from the beer. I feel that it is rather empty compared to a commercial Helles or Maerzen. And the finish still felt a little to harsh. And there is a pesky slight dustiness that I'm occasionally getting from my beers.

So I gave a Helles a try and made sure that I pay attention to all the details that I know could make a difference and which I could take care of w/o bying new equipment:

• use a heated step infusion mash with a 57 C (137 F) dough in and a 2 step saccrification rest. 63 C Maltose rest and then an extended (60 min) rest at 70 C, which is said to be beneficial for body and head retention. This is pretty much as authentic German as it gets and this would be a first for me since it doesn't really fit my brew-house. But I can make it work.
• when batch sparging don't drain the wort below grain level. This is basically in response to the BYO article about sparging
• fix the manifold seal for my MLT. Recently I started pulling in air through this.
• add hops before the hot break and maybe even FWH the batch. Hopefully this smoothens out the finish
• 90 min boil
• DMS rest. When I have an imported Helles it generally has a tad of a sweet aroma. It doesn't smell like the typical DMS aroma to me, but I could imagine that it is DMS which is barely at the aroma threshold. So far I have been chilling my beers below 100 within 10 - 20 min. No Commercial brewery that has a whirlpool can do that and I want to know if this is the reason why my beers have such a clean (=empty) aroma. I'll have to read up on average time that commercial wort is spending hot.
• 12+ hr post chill whirlpool settling. For that I will chill the wort to ~48F and keep it in an ice bath for the next 12 hrs before racking to the fermenter. This is supposed to get rid of about 60% of the cold break. Commercial brewies may have settling tanks for this. And since I don't have a conical I have to go this route.
  

These were a lot of changes, but If the beer really comes out different (and hopefully better) I could start eliminating one extra step after another to figure out what is actually important.

Here is the result:

The first surprise was, that there is great hop flavor and aroma even though all the hops were added before the start of the boil. First wort hopping does work! But the hop utilization was better than expected, so it became more of a Pilsner than a Helles.

I can't detect any DMS in the beer. The DMS rest didn't work, but I found that aged beer may develop a sweet aroma. It's likely that I'm getting this when having a German beer here in the US. Besides this, I had a Spaten Maibock on tap a few days back and its aroma was very similar to my lagers. I seem to be on the right track.

The step mash didn't make a dramatic difference since I cannot taste a difference that I would contribute to that. It may take a side-by side to verify this. But the head retention is good. Difficult to tell if his is a result of the long rest at 70 C.

I used the Bavarian lager (WY2206) for this, since this was the only yeast I had on hand at the time and had to push it hard (i.e. warm maturation rest) to get close to the limit of attenuation. But it didn't want to and stalled 0.5 Plato shy of it:

original extract: 12.0 Plato

limit of attenuation: 82% (fast ferment test AE=2.2 Plato)

beer attenuation: 77% (beer AE=2.7 Plato)

The target for the aparent extract of the beer was 2.5 Plato, and as a result of actually being higher than that the beer is a little sweeter than I'd like it to be. But I know to fix this with a different yeast next time.

I didn't see any benefit of the more complete trub removal. According to some studies and other home brewer's experiments, its importance seems overstated anyway.

The pesky "dusty" taste still exists. But since it only happens when I drink the beer that stood in the beer line for a day, I suspect it is staling in the beer line.

This year's Maibock came out really nice (recipe). The only thing I'll have to change next time is to use a different yeast to make sure it attenuates better. The yeast I used was the Wyeast 2206 (Bavarian Lager) which has a really hard time when it comes to getting the attenuation closer to the limit of attenuation. This leaves more fermentable sugars in the beer which results in an increased sweetness. And maybe I'll also reduce the amount of dark munich from 20 to 15%, to lighten the color.

The beer was actually much more cloudy shortly after I filtered it, but it cleared nice in the keg since then. The filtration was done with a 1 micron (nominal) spun sediment filter.

Stats:

original extract: 16.5 Plato

limit of attenuation: 82% (fast ferment test AE = 3.0 Plato)

actual attenuation: 75% (beer AE = 4.1 Plato) 

Today I brewed the wort for one of my Weissbier experiments (70% light wheat and 30% Pilsner malt). During that brew session I also conducted an experiment to test for enzymatic activity during mash-out. I felt that this was necessary since even some knowledgeable folks (BYO Wizard) seem to disagree with me on that subject.

The used mash schedule was a Hochkurz mash:

45 min at 63C (145F) - Maltose rest

15 min at 70C (158F) - Dextrinization rest

10 min at 76C (169F) - mash-out

The the dextrinization rest was reached with a boiling water infusion and the mash-out was reached with a thin decoction. After 10 min mash-out I filled a small 20 ml vial like the one on the right.

 with a gelatinized wheat starch solution (about 20%) and wort from the mash (about 80%). I did the same with a control where I added water instead of the wort. Both vials were thrown into the mash, where they quickly reached the current mash temperature of 76C. After about 10 min the wort filled vial showed a significantly weaker iodine reaction than the control and at the end of  the ~30 min sparge the wort filled sample was converted. Here is what the iodine test looked like at the end:

The control shows a significant reaction between the starch and the iodine whereas the sample doesn't show any reaction between starch and iodine. There is a faint reaction of the dextrines (reddish brown color) visible. The black spot next to the sample was already there.

 As a result of this experiment, I'm convinced that there is still significant enzymatic activity potential during mash out.

I have to start pushing this test more. It seems as if it provides an answer to one of the most common brewing forum questions: Why is my FG higher than expected? Interesting enough, most of the very experienced American home brewers don't use this test either. Might be that their process is refined enough that the information given by this test is just redundant. But especially for beginning homebrewers, this test can provide invaluable information regarding the FG that can be expected. Almost as important ad taking an original extract (OG) reading. To many of them are just hung up on the attenuation numbers that are given for the yeasts at White Labs and Wyeast. When I asked them about the procedure that is used to get these numers, they told me that they don't even use a standard wort for all the yeasts.

I certainly swear by it. How else can you find out if you met your targeted fermentability during mashing before the beer fermentation is done. It has become very important to brewing lager beers as they seem to slow down significantly towards the end with a risk of being to sweet before going to lagering temps. But even with Ales this test is useful as it actually allows me to take residual fermentable sugar in the beer into account when calculating priming sugar additions.

Mainly to show myself the taste differences between beers brewed with a double decoction (which includes a thick decoction) and a beer brewed with a single decoction (thin decoction), I brewed 2 Maibocks this year (last year I realized that I need 2 and making a decoction experiment out of them seemed natural). The recipe was this:

• 73% Bohemian Pils
• 20% Munich Type II
• 2% acid malt
• 2.3 % CaraVienna
• 2.7% Cara Hell
  
• Hops to get to ~21 IBU (Tinseth formula)

Mash 

The first beer (A) was brewed using a Hochkurz deoction like this:

• with these mash parameters:
• dough-in/protein rest: 54 C (131 F) for 15 min
• maltose rest: 63 C (145F); a thick decoction was pulled after 30 min
• decoction was converted at 73 C (163) and the total time from pulling to boil was 30 min
• 10 min decoction boil
•  dextrinization rest 70 C (158 F) for 15 min (until iodine negative)
• 2nd decoction was pulled, brought to a boil in 12 min and boiled for 2 min
• mash-out was at 77 C (171 F) 

The second beer (B) was  brewed with a step infusion and thin mash-out decoction. I just noticed that when I read my notes. When coming up with the experiment I thought that it would be sufficient to check for an impact of the thick decoction where grain is actually being boiled. The mash-out seemed more important than having a true non-decoction beer.

• dough-in/protein rest at 55C (133F) for 20 min
• saccrification rest at 65.6 ( 150 F) for 45 min
• thin decoction pulled and brought to a boil within 15 min
• boiled for 5 min
• mash-out at 73 C (163 F)

Fermentation 

Both beers were fermented with the same temperature profile. But the 2nd one was pitched with yeast from the first one since they were brewed about 10 days apart. The fast ferment test for the double-decocted beer (A) showed a final extract of 3.0 Plato (82% limit of attenuation) and the fast ferment test for the beer (B) showed a final extract of 3.4 Plato (80% limit of attenuation)

About 2 months later, both beers didn't show the reduction of extract during lagering that I hoped for and fresh yeast was added to kick start another fermentation. They were also moved to a 15 C area for 3 days to speed up that fermentation. At the end they reached 4.3 Plato and they were both moved back to the lagering fridge. After another 3 weeks the double-decocted beer reached 4.1 Plato and was racked to a serving keg. The single-decocted beer was still at 4.4 Plato and was moved to a 5C fridge to speed up the fermentation that was still going on during lagering. After another 2 months the single decocted beer was finally not to sweet anymore and racked to a serving keg. Its extract was now at 4.1 Plato.

Tasting 

Shortly after racking the single-decocted version to the serving keg, I tasted both beers. The keg with the double-decocted version was already empty and I had to take it from a bottle. The single decocted version was taken from the keg.

There was no noticeable difference in color between the two beers. That is not surprising because the difference in decoction boil time was only 10 min (I know, I should have extended that to 30 min). The double-decocted beer showed a slight bit more haze, but only because it was actually colder (about 4C compared to the  single-decocted beer that was at 8C).

The head retention was comparable, but was not evaluated due to the differences in carbonation between the beers.

The double-decocted beer was a little sweeter and maltier in its aroma. I'm hesitant to contribute this soley to the decoction. Both beers ended up being treated slightly differently towards the end of their fermentation and many of the sweet aroma notes come from compounds produced during the aging of the beer.

Both beers started malty sweet and didn't have any lingering bitterness. A balance that is typical for a Maibock. But the double-decocted beer was considered to have a more "robust" finish. While this can be a result of the additional decoction boil, it can also be the result of fermentation byproducts like higher alcohols. This "robustness" was also confirmed in degassed hydrometer samples and is thus not a result of different carbonantion. The single decocted beer seemed more "flat" in comparison.

Conclusion

While a difference between the two beers exist, it is slight and could easily caused by different fermentation parameters. But it could also be the result of the decoction. In the end this experiment neither showed that there is no difference between decocted beers, nor did it show a flavor difference that can conclusively be attributed to the mashing difference. Additional experiments are necessary for that. Such an experiment should be done between a mash that heavily uses decoctions and boils them for a longer time and a mash that does not use decoction at all but holds all the rests that the decoction mash was holding. Preferably for a daker beer as these are the beers where decoction is most common in German breweries these days.