My Brewing Log

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.

.... and the German brewing authors I read so far: http://www.byo.com/mrwizard/1391.html (2nd topic) 

Most likely it was me who was spreading the word on the forums that a mash-out at 76 – 78 C (169 – 171 F) doesn’t kill all enzymes and is also not supposed to. I find this in all the German brewing texts that I read so far and even the ones I didn’t read say the same, according to the German homebrew forum.

 The interesting thing is, that it doesn’t really matter why you believe the mash-out limit is 170F. The American literature (I have only read homebrewing stuff) seems to suggest that this limit is due to excessive tannin extraction at higher temperatures while the German authors emphasize that enzymatic activity needs to be preserved in order to convert additional starches that are released by the lauter process. At the end, both views will have you mash-out below 170 and you will be doing the right thing.  

Today I ran some more pH experiments. In particular a test against the colorpHast strips that I did about 1 1/2 years ago when I got the pH meter (results were posted here). For a while now I cannot calibrate the meter (a Milwaukee pH53) anymore as it will not recognize accept the calibration solutions. It has never been easy to calibrate that meter. That's why my next meter will have little knobs for calibration.

So I had to do the 2-point calibration by myself. The 4.01 buffer read at 4.29 and the 7.01 buffer read at 6.98 (all temps at 62F). Based on that I calculated the slope and offset to get the corresponding pH for a measurement. I then used vinegar and baking soda to mix buffer solutions of various pH which I tested with the meter and pH strips:

 and the graph

Very odd was the measured range of 4.5 .. 5.3, where the strips alwasys read 4.7 (read in tungsten light) I ran the test a few times and I also had to add baking soda to increase the pH of the solution. But even though the reading of the pH meter went up, the reading of the strips remained at ~4.7 pH. I may have to rerun this experiment with mixing the 4.01 and 7.01 buffers as I did it initially, just to take the different types of test solution out of the mix. But pH should be pH regardless of the medium.

I then went on to test the temperature sensitivity of the pH meter, and there is actually one. The same solution at different temperatures, showed these different readings (not corrected for calibration):

61F -> 5.27

90F -> 5.31

100F -> 5.36

I was also curious of the temperature dependency of the strips and found this result:

60F -> the strip matched the color for 4.7

140F -> the strip matched the color for 5.0

The odd thing is, that the reading at the higher temperature is higher even though it is commonly assumed that the pH is lowered with increased temperature. The one submerged in cold solution was definately more yellow than the one in the hot solution. Based on that I will now always make pH readings with the strips on cooled samples. When I pulled the strips out, which allowed the one immersed in the 140F solution to cool, both strips colors seemed to settle at 5.0. This was unexpected. I would have thought that they settle at 4.7 or keep their color.

Looks like as if these experiments seem to bring up more questions than answers.

I just did an inventory of my yeast bank

Lagers

• WY2006 - Bavarian Lager (Weihenstephan 206)
• WY2042 - Danish Lager (Miller via Carlsberg)
• WY2007 - Pilsen Lager (Budweiser)
• WLP800 - Pilsner Lager Yeast (Pilsner Urquell)
• WLP833 - Bock Lager (Ayinger Brewery)

• WY1007 – Alt (Zum Uerige)
• WY1056 - Cali Ale (Sierra Nevada (Seibel 96))
• WY2565 – Koelsh (Weihenstephan 165)

• WY3056 - Bavarian Wheat; this one is a blend. Let's see what I get from a single cell growth propagation. With some luck I get the wheat strain and not the neutral ale strain.
• WLP300 – Hefeweizen (Weihenstephan W68)
• WLP351 - Bavarian Weizen (Weihenstephan W175)

I took the likely origins from Kristen’s yeast strain chart.

I have been wondering about this for a while now, when I read German texts and papers, the mash and wort pH values are generally close to 5.5 or even above that while common wisdom in American home brewing seems to be 5.2 - 5.4. First I thought that this had to do with the temperature shift that happens to the pH when the temperature is increased, but that doesn't seem to be the case since Palmer explicitly states that his pH references are for 25 C. Also, the pH optimas listed for the amylase enzymes listed by Palmer and Narziss don't seem to match up. I don't know what's up with that, but my currect position is that there is a fairly wide pH range that can be explored to see how the taste changes.

 Currently I aim for 5.3 - 5.4, but find that the beers don't quite have the taste that I'm looking for. Maybe being closer to 5.5-5.6 may give me what I'm looking for. 

 I also added this to the Wiki:

• Temperature dependency of the pH measurement
• Mash pH target

 And plan to maintain that information as my understanding of the subject changes.

 I also took the time to check if my pH meter's (made by Milwaukee) temperature correction includes the pH change that happens with temperature (as opposed to just the temperature error of the sensor). A warm (100 F) and a cold (50 F) beer sample both read 4.55 +/- 1 on the meter. I guess that means that the pH change based on temperature is compensated for. Yet another yeason to assume that the pH values given in the literature are most likely values based on room temperature measurements.

I recently came across the dissertation of Markus Herman. Though most papers that I find have little application in home brewing this one was a very interesting one as it deals with controlling the various aroma aspects of Bavarian Wheat beers. This gave me the idea to get a better understanding in brewing a Bavarian Wheat beer, which will require me to make this a Summer of wheats.  At the beginning of April I got a 25kg bag of Weyermann wheat and one of the wheats is already done with the primary fermentation.

 Temperature control gives me a little headache right now. The basement is to cold (14 C) and the house seems to be to warm (20 C). I'll have to figure out how to get this worked out.

 And the best thing of this Summer is going to be our trip to Bavaria. Finally I can get my palate reset when it comes to how do  German beers have to taste. Last November's trip helped a little, but this will be better.