[Kaiser]

It took much longer that I thought it would take. Not only because I took a break from brewing and writing about it for a while, but most importantly I wanted to write an article that is well supported by brewing experiments and close observations of mash pH in batches of beer that I brewed over the last year. All too often get brewers caught up in the theoretical aspect of water and mash chemistry with the aim to calculate everything with the best precision possible. But what is commonly overlooked is that measurements are not precise enough to require this precision and, what is mots important, malt’s reaction to pH changes is not that predictable anyway. To capture that aspect experiments are necessary.

The objective of this article was to give the advanced brewer an insight in the major factors that affect mash pH and how it can be corrected. Based on experiments it also gives guidelines that allow the estimation of mash pH changes based on the water profile, water treatment additions or mash additions, without focusing too much on this aspect. Those are largely based on mash pH experiments I conducted including the data published in The effect of brewing water and grist composition on the pH of the mash.

With this article I also released a updated version of my water calculator. But more on this later.

Click here: Mash pH control

Kai

[bluesman]

Impressive work Kai...I haven't digested all of yet but I'm sure I will reference it from time to time. An awesome contribution to our craft.

Looking forward to the updated water calculator as well.

Very nice work!

[nateo]

Really fantastic work Kai! Maybe people will stop using those Palmer SRM spreadsheets now. . .

[denny]

Thanks so much for all your work on this and your revised water spreadsheet, Kai.  Today, I'm ignoring pH since my meter seems to have gone wacky!

[tomsawyer]

Very nice article Kai.

In the distilled water pH vs color graph, your 2-row looks like an outlier.  What about the wheat?  Is it really that high all the time?

In the discussion about using phosphoric acid to bring down pH, I'm not sure I'd agree that it wouldn't cause precipitation.  A lot of the malt phosphate is as phytin which is insoluble and more limited in its exposure to the soluble Ca.

Those are just a couple points I ran across this morning.  I'm not being critical, just generating a discussion of your fine work.

[mabrungard]

I am in Kai's camp regarding the low potential for phosphoric acid additions to cause calcium precipitation.  A.J. Delange, Colin Kominski, and I had a discussion on the Brewing Network forum about a month ago on this subject.  The bottom line was that the minor addition of phosphate ions to the mash, pales in comparison to the amount of phosphate supplied to the mash from the grain. 

It does not appear that phosphoric acid causes calcium precipitation or is a very minor contributor to the reactions that take place naturally. 
 

[tomsawyer]

So does this mean that it is the preferred acid for pH adjustment then?  It doesn't supply flavor components like HCl, H2SO4 or lactic acid, and the phosphate is usable by yeast although you're saying this isn't a signficant benefit since there is plenty of phosphate in the mash anyway.

I have some 10% phosphoric acid I got from Northern Brewer, I may begin using it instead of lactic.  Thanks Kai for providing an estimate for addition per gallon, relative to the other acids.

[Kaiser]

In the distilled water pH vs color graph, your 2-row looks like an outlier.  What about the wheat?  Is it really that high all the time?

I made a note that the 2-row is Rahr 2-row. But I don’t know yet how universal these numbers are. They should be seen as a snapshot and are mostly to illustrate how low the correlation between color and base malt pH is.

In the discussion about using phosphoric acid to bring down pH, I'm not sure I'd agree that it wouldn't cause precipitation.  A lot of the malt phosphate is as phytin which is insoluble and more limited in its exposure to the soluble Ca.

I agree with what Martin stated about this. And I have done some experiments that showed that phosphoric acid doesn’t change the pH more or less than lactic acid. However, there is always room for fluctuations.

Those are just a couple points I ran across this morning.  I'm not being critical, just generating a discussion of your fine work.

I appreciate that. Since it is on the web I can easily update it once I get a better understanding about a particular topic.

So does this mean that it is the preferred acid for pH adjustment then?  It doesn't supply flavor components like HCl, H2SO4 or lactic acid, and the phosphate is usable by yeast although you're saying this isn't a signficant benefit since there is plenty of phosphate in the mash anyway.

I have a strong influence by from German brewing where lactic acid is the preferred and the only acid that is used for pH correction. As a result I prefer lactic aicd and have been advocating its use. I only recently started phosphoric acid just to see if there is a difference. In fact my current double batch of KaIPA will be done with phosphoric and lactic acid as a side-by-side.

I have some 10% phosphoric acid I got from Northern Brewer, I may begin using it instead of lactic.  Thanks Kai for providing an estimate for addition per gallon, relative to the other acids.

It’s also included in the table that shows how much to add per kg or lb of malt to lower the pH by 0.1. I used this number recently and the pH dropped a bit more than expected. I’m not sure what was up with that, though and don’t want to attribute it to increased Ca precipitation at this point.

Kai