Mash pH and Kettle pH

[mchrispen]

Since we have derailed a couple of threads on this topic, I thought it helpful to start a new thread, properly titled to discuss. AND I have a few questions...

1.) Optimal mash pH recommendations seem to change dependent on light or dark beers. Is this only because of the differing buffering capability of the different mash recipes? I tend to mash toward 5.2 for softer styles, middle at 5.4 for APA and IPAs, and a bit higher 5.5/5.6 for darker beers. This maybe completely wrong, but seems intuitive.

2.) Sparge acidification seems to be determined to prevent rising pH and the extraction of tannin and phenols during sparge. However, this process would seem to naturally have the affect of lowering the boil kettle pH as well - or creating a new buffering system there at least. Am I more or less correct in assuming that liquid acid additions to the sparge are fundamentally additions into the kettle? Not sure if sparge process affects this at all (batch vs fly) given different contact times with the mash.

3.) I am MOST curious now about the boil kettle pH. I have observed pH drops particularly at initial hot break, as well as during hop additions. There seem to be some different opinions on "ideal" kettle pH, relative to given beer styles or hop types (noble vs american high alpha), etc. How, based on a given recipe, should we identify the ideal boil pH or the target going into the fermenter, and I assume manipulate to acheive a target?

Relative to #3, I manipulated a boil to 5.4 for a recent APA, while I have let my previous brew, a saison to drop below 5.2. Both have turned out fantastic (IMO), but have wildly different hardness and bitterness profiles. Are there recommendations that are style driven, hardness/alkalinity driven, or is this taking my pH meter into the extremes of nerdiness?

 

[ajdelange]

1.) Optimal mash pH recommendations seem to change dependent on light or dark beers. Is this only because of the differing buffering capability of the different mash recipes? I tend to mash toward 5.2 for softer styles, middle at 5.4 for APA and IPAs, and a bit higher 5.5/5.6 for darker beers. This maybe completely wrong, but seems intuitive.

Mash pH needs to be controlled so that all the enzymes work at optimum efficiency. As there is no pH at which that can happen we then have to tune for a mash pH that produces the 'best' beer under our personal definition of what 'best' means. A beer mashed at pH 5.2 will either be better than, worse than or the same as one brewed at pH 5.6. You need to figure out which is the case IOW you would have to experiment to find where in that range you get the beer that most pleases you. I do know from experience that my beers improved dramatically as I lowered pH from 5.6 to 5.4 - 5.5. I should have kept going but I didn't (I just don't brew that much any more). I have no reason to expect that my beers would get better if I went lower in pH but I have to assume that at some point (below 5.2?) things would start to get worse. There are those that will try to convince you that a lower mash pH implies a lower beer pH and that therefore you should have a certain mash pH for a certain level of acidity in the beer but this is largely not true as the yeast tend to smooth out any variations from wort pH. As in any feedback regulated mechanism regulation isn't 100 % but if your wort pH drops 0.3 your beer pH shouldn't be lower by anything nearly that much.

2.) Sparge acidification seems to be determined to prevent rising pH and the extraction of tannin and phenols during sparge. However, this process would seem to naturally have the affect of lowering the boil kettle pH as well - or creating a new buffering system there at least. Am I more or less correct in assuming that liquid acid additions to the sparge are fundamentally additions into the kettle? Not sure if sparge process affects this at all (batch vs fly) given different contact times with the mash.

I think you are more or less correct. If you add acid to water which you then add to the beer the proton surfeit associated with that acid has to be counted against the total proton deficit but, if you sparge with distilled water in one batch and with water of alkalinity 2 mval to which you have added 2 mval acid the results should be the same (in terms of kettle pH).

3.) I am MOST curious now about the boil kettle pH. I have observed pH drops particularly at initial hot break, as well as during hop additions.

That's quite normal. Drops of 0.1 - 0.3 pH are to be expected. Looking back in my log I find an average drop of 0.29.

There seem to be some different opinions on "ideal" kettle pH, relative to given beer styles or hop types (noble vs american high alpha), etc. How, based on a given recipe, should we identify the ideal boil pH or the target going into the fermenter,

You should brew at various pH values and determine which gives you the beer you like best. But as you have finite time and resources your ability to do this is limited. Therefore, I would recommend going to the literature and seeing what is standard for the industry. Most of my texts say 5 - 5.2. You can, of course, find different opinions. I won't presume to tell you who is right and who is wrong as it really depends on what you like.

..and I assume manipulate to acheive a target?

Most brewers find that proper management of mash pH will result in a knockout pH in the proper range. Those that want lower levels will add calcium salts or even acid to the kettle. Those who want higher mash pH add alkali (but I have to admit I have never heard of anyone doing this before).

Are there recommendations that are style driven, hardness/alkalinity driven, or is this taking my pH meter into the extremes of nerdiness?

Yes, there are recommendations but the question is as to their validity vis a vis your personal criterion of goodness. A quick review of the literature (i.e. the big name texts) didn't turn up any 'do this for lager and do this for ales' advice nor in fact did I in an admittedly cursory check find British books and German books at odds on this. If you want better coagulation, less color deepening, better diacetyl management, less astringency, better biological stability... and are willing to pay a bit extra for hops to get a given level of IBU's then go to lower levels (but not too low). If, OTOH, you need to squeeze every milligram of alpha acid out of each dollar's worth of hops, you don't mind or even like astringency, don't care about coagulation of cplor development that much then go higher. But be sure to taste test!

 

[mchrispen]

So after rereading through Kai's discussion on pH in brewing, he seems to conclude the following:

1.) Mashing between 5.3 and 5.8 is sufficient for most mashes, but grists with strongly enzymatic malts are "well suited" between 5.2 and 5.5, weak enzymatic mashes and decotions should be above 5.4
2.) Mash pH and Kettle pH are tied together, and pH during the sparge should not rise above 5.8 (risks tannin and polyphenol extraction). This could also be avoided with a higher grain to liquor ratio to limit sparging, using DI or RO for sparge or acidification of sparge water to 6.
3.) He states that common boil pH is between 5.2 - 5.4 (quotes Narziss, 2005) and that the boil typically drops 0.1-0.2 pH units during a boil to 5.2-5.3... which is a balance between break formation, hop utilization, maillard reactions and benefits clarification with irish mosh or whirlflock

Palmer tightens mash pH recommendations between 5.2 and 5.6, I cannot find any comments on boil pH, but still looking.

Chris Colby takes a similar take, but essentially sees pH 5.2 as optimal for break formation, and finishing closer to 5.1

In digging deeper, I did find a comment on a board (hdb.org) that references Colin's statement about raising the pH to "mid-5's" when he starts to taste grassy notes in the boil.

It seems procedurally, measuring wort pH out of the mash tun, at boil (hot break formation), and into the fermenter are common. It does seem if one wished to change the wort pH in the process, perhaps an additional measurement should be added at 15 minutes before flame out. I am also wondering if large hop additions at flameout/whilrpool also affect final pH.

Time to dig out my George Fix...

 

[ajdelange]

1.) Mashing between 5.3 and 5.8 is sufficient for most mashes, but grists with strongly enzymatic malts are "well suited" between 5.2 and 5.5, weak enzymatic mashes and decotions should be above 5.4

I recall (vaguely) comments in Kunze that lager beers are often mashed at higher pH's than ales and remember thinking that made sense because before I started using sauermalz and RO water the pH used to drop at each decoction. That no longer happens.

3.) He states that common boil pH is between 5.2 - 5.4 (quotes Narziss, 2005) and that the boil typically drops 0.1-0.2 pH units during a boil to 5.2-5.3... which is a balance between break formation, hop utilization, maillard reactions and benefits clarification with irish mosh or whirlflock

Narziß definitely favors lower kettle pH (SMM reduction is another factor I had forgotten about) but we need to remember that when we say 5.0 - 5.2 (best range for protein coagulation, SMM, and hop aroma retention according to him) that is at the end of the boil. If properly mashed the wort should have a pH of 5.4 - 5.5 going into the kettle. Drops of 0.1 - 0.3 pH are to be expected.

It seems procedurally, measuring wort pH out of the mash tun, at boil (hot break formation), and into the fermenter are common.

There is a very good reason for doing this that is often overlooked. In the first few hours of fermentation, before any physical signs are evident, the yeast will plunge the pH of the wort. If I pitch at 6 PM, check wort pH at 11 and find its dropped a few tenths I know I'll have a healthy ferment going in the AM (my fermenters are stainless so I can't see what's going on inside).

 

[mchrispen]

So finally found my "Principles of Brewing Science" and have done a cursory review of pH discussions. Essentially - Fix elaborates heavily on mash tun reactions, and about the role of pH in determining protease and alpha/beta amylase activity, but doesn't appear to make a specific range recommendation, with the exception of a reference to Hinde, 1950 - expecting between 5.2 and 5.4 in the mash tun and Table 1.9 illustrates effective Alpha Amylase activity at specific pH ranges from 4.8-6.2. The only other recommendation I can find is that sparge should never exceed 5.5 and to use very low alkalinity sparge water.

Surprisingly, I can find no discussion of pH in the boil kettle or in the fermentation section. With the discussion of hops utilization here, I would have thought some correlation may have been discussed. I guess that there are some assumptions being made - namely that the biochemical and chemical reactions are assumed to occur in optimal temperature and pH conditions. This seems more of a scientific introduction academic book - good read when I can concentrate and try to follow the chemistry.

 

[ajdelange]

Fix's book(s) aren't really comparable to Narziß, Kunze, deClerck, Priest, Stewart, Briggs, Hough.... His was an introduction to brewing science for home brewers. It's cursory, contains several mistakes and the topic selection is strange. I got him really, really PO'd once by asking why, after vigorously arguing in another context that yeast never ever respire, he had devoted a whole chapter to the TCA cycle in his book.

 

[mchrispen]

It's going to be difficult to access the authors you mention - I have searched, and really can only find a few papers - some of which are not in English. I guess I should just join the Brewer's Guild and see if I can access more detailed information.

Brewing again this week so also researching that and prepping.

 

[ajdelange]

These guys have written tons of papers but here I am thinking of them as book authors. Look on Amazon and elsewhere for titles like deClerck's "Textbook of Brewing", Hough, Briggs, Stevens and Young's "Malting and Brewing Science", Priest and Stewart's "Handbook of Brewing Second Edition" (and Hardwicke's first edition of the same title - its a separate book really) and Briggs, Boulton, Brooks and Steven's "Brewing Science and Practice". Kunze you can get in English from VLB and Narziß from Amazon.de but be sure to have your Cassel's handy (no English edition that I am aware of).

Briggs, Boulton, Brooks and Stevens, which I had forgotten about, indicates all the benefits of low kettle pH, mentions reduced hops utilization as an exception to this and mentions that pre isomerized extracts are the way around that problem. As I can't see myself saying "Hey, Derek, give me a pound of pre-isomerized Saaz" I just say, "Hey, Derek, give me 2 lbs of Saaz". Problem solved.