Wort pH adjustment has relatively little to do with final beer pH

[Silver_Is_Money]

I came across an article (link below, "BAMFORTH-pH-in-brewing") which references a work by D.G. Taylor (1990) titled "The importance of pH control during brewing" wherein it was found by Taylor that wort pH adjustment has relatively little to do with final beer pH. Perhaps this means that those actively chasing kettle pH via adjustment are not necessarily accomplishing what they think they are accomplishing.

Actually, adjustment of wort pH has relatively little impact on beer pH [57] . The critical factors are the buffering power that survives the fermentation and the extent to which acid/H+ is produced during fermentation.

http://********************/wp-content/uploads/2016/11/BAMFORTH-pH-in-brewing.pdf

Just tossing this out for comments and open discussion....

 

[Big Monk]

I came across an article (link below, "BAMFORTH-pH-in-brewing") which references a work by D.G. Taylor (1990) titled "The importance of pH control during brewing" wherein it was found by Taylor that wort pH adjustment has relatively little to do with final beer pH. Perhaps this means that those actively chasing kettle pH via adjustment are not necessarily accomplishing what they think they are accomplishing.



http://********************/wp-content/uploads/2016/11/BAMFORTH-pH-in-brewing.pdf

Just tossing this out for comments and open discussion....

I don't think people adjusting kettle pH really care about it's affect on final beer pH. At least I don't. I do a KO addition to get to pH 5.0 to speed up the onset of fermentation. Yeast have to first drop the pH initially to get "cruisin'" and I want to help them get going because the less time the beer stays exposed to oxygen without active yeast the better.

 

[Silver_Is_Money]

I don't think people adjusting kettle pH really care about it's affect on final beer pH. At least I don't. I do a KO addition to get to pH 5.0 to speed up the onset of fermentation. Yeast have to first drop the pH initially to get "cruisin'" and I want to help them get going because the less time the beer stays exposed to oxygen without active yeast the better.

That makes good sense. Thanks RPIScotty!!!

 

[cire]

There is an abstract from The Importance of pH Control During Brewing to be seen here.

 

[ajdelange]

Not a particularly informative paper. His definition of buffering (∆acid/∆[H+]) is a little naive (though Bamforth uses it too). ∆acid/∆log[H+] = ∆acid/∆pH recognizes that natural systems tend to respond to the logs of stimulae. The paper starts with the notion that we should be thinking in terms of [H+] when in fact we should be thinking in pH. That's why Sorensen came up with it.

 

[SanPancho]

I don't think people adjusting kettle pH really care about it's affect on final beer pH.

many brewers adjust in the kettle, especially the knockout pH in order to "pre-adjust" the final beer for the pH rise caused by dry hopping. IIRC the pH rise is considered to be roughly 0.15 per # per bbl. significant on the hoppy beers.

 

[Silver_Is_Money]

Kai Troester seems to imply that the more calcium present within the mash water, the lower the final beer pH might be. He theorized that a high level of calcium erodes existent buffering capacity, and thereby the yeast can achieve a lower final beer pH. I don't know if he ever proceeded to conduct experiments to prove out this speculation.

Another interesting aspect with calcium is that it precipitates phosphates which are a major pH buffer in wort and beer. It is very much possible that a beer brewed with calcium rich water can end up with a lower pH compared to the same beer brewed with water low in calcium even if they both had the same mash pH.

Kai Troester, https://www.homebrewersassociation.org/forum/index.php?topic=4875.15

I will only add that to my knowledge Pilsner Urquell is mashed and sparged in calcium deficient water, and it winds up having one of the highest finished beer pH's among all commercial beers.

 

[SanPancho]

really interesting. so obviously gypsum and chloride rich mashes would fit the bill. but with half the calcium typically getting tossed with the grist, does that mean you should go high with Ca in the mash, or really high?

 

[doug293cz]

really interesting. so obviously gypsum and chloride rich mashes would fit the bill. but with half the calcium typically getting tossed with the grist, does that mean you should go high with Ca in the mash, or really high?

How do you come up with "half the calcium typically getting tossed with the grist"? We typically collect ~85% of the water used in brewing in the BK (for batch sparge and no-sparge), thus we should also collect about 85% of the calcium that was in the brewing water (this is over simplified, but not terribly inaccurate), which is way more than 50%

Brew on

 

[SanPancho]

How do you come up with "half the calcium typically getting tossed with the grist"? We typically collect ~85% of the water used in brewing in the BK (for batch sparge and no-sparge), thus we should also collect about 85% of the calcium that was in the brewing water (this is over simplified, but not terribly inaccurate), which is way more than 50%

Brew on

read Kunze.

then "brew on"

 

[doug293cz]

read Kunze.

then "brew on"

Not helpful.

Brew on

 

[Silver_Is_Money]

If one allows that in general more calcium is permitted in the mash and sparge waters for ales than for lagers, and if one agrees with Kai Troester's reasoning that more calcium leads to the potential for yeast to additionally reduce finished beer pH, then this might at least partially explain why lagers generally finish with higher pH's than do ales. Finished beer pH may not have as much to do with yeast species as once thought.

With this in mind, how far can one push calcium without noticeably altering flavor?

 

[Silver_Is_Money]

I just noticed that the D.G. Taylor quote I started this thread with already stated essentially the same thing which Kai is stating. That the key to low finished beer pH is to break down the buffering power. High initial calcium is a means to this end.

 

[cire]

I just noticed that the D.G. Taylor quote I started this thread with already stated essentially the same thing which Kai is stating. That the key to low finished beer pH is to break down the buffering power. High initial calcium is a means to this end.

He also wrote the Water chapter in the third edition of the Handbook of Brewing. Most of that chapter can be read on Google Books. It starts halfway through the available text.

Taylor also wrote another chapter in that book, but not that on fermentation. It was interesting to observe in the chapter on fermentation, from, memory, pH was never mentioned.

 

[ajdelange]

Kai Troester seems to imply that the more calcium present within the mash water, the lower the final beer pH might be. He theorized that a high level of calcium erodes existent buffering capacity, and thereby the yeast can achieve a lower final beer pH.

The problem with that theory is that phosphate doesn't buffer appreciably in the beer/mash pH range

pH Charge on 1 mmol of PO4
4.3 -0.9942276
4.4 -0.995990383
4.5 -0.997544295
4.6 -0.998969994
4.7 -1.00034185
4.8 -1.001731581
4.9 -1.003211785
5.0 -1.004859511
5.1 -1.006759984
5.2 -1.009010614
5.3 -1.011725396
5.4 -1.015039773
5.5 -1.019115993
5.6 -1.024148899
5.7 -1.030371948

I don't see much buffering there. Do you?

The buffering at mash/wort/beer pH comes from the other acids in malt. That doesn't mean phosphate doesn't buffer. It just doesn't buffer at mash/wort/beer pH.

pH Charge on 1 mmol of PO4
7.0 -1.386854156
7.4 -1.613143534

 

[Silver_Is_Money]

The problem with that theory is that phosphate doesn't buffer appreciably in the beer/mash pH range

I don't see much buffering there. Do you?

And here I thought I was on to something. The bubble has burst. I guess I've always placed too much trust in Kai being correct in all of his reasoning....

 

[cire]

A presumption that calcium deposits with phosphate and plays no other part bursts that bubble.