Pre Dough-in pH puzzle

[Sudz]

I've been brewing for a number of years using the 5.2 buffer. Never an issue of which I was aware... but

I thought I'd attempt to adjust the pH using Bru'n Water calculations and forego the 5.2 Curious to see if I could tell a difference.

I've been adjusting water minerals for some time and do have a monthly water report to utilize. We have fairly good brewing water that's just slightly high on the total alkalinity. Mineral adjustment very basic.

Utilizing Bru'n Water I crunched the numbers and found I needed 52 ml of 10% phosphoric acid to hit a mash pH of 5.4 (7 gal brew of a Belgian Wit - no sparge).

I prepped my mash water with the minerals added and checked the pH with a cal'd meter at room temp. It was 7.06. I then added the 52mls of phosphoric acid and checked again prior to heating for the mash.

The pH was 3.98?? I expected the pH to be higher than my mash target of 5.4 since the grain would surely drop the pH. I was not comfortable adding the 52mls so I slowly added acid until I hit about 5.8 pH.

At this point I went ahead and heated for the mash and once it was started slowly added more acid in steps. Over about 30 minutes I had added most of the 52 ml and observed a reasonable pH of about 5.5. The mash actually completed in good shape. Time will tell on the brew I guess.

Here's my question... Is it normal for the pre-mash water to have such a low starting pH before heating and dough-in?

 

[ajdelange]

I prepped my mash water with the minerals added and checked the pH with a cal'd meter at room temp. It was 7.06. I then added the 52mls of phosphoric acid and checked again prior to heating for the mash.

The pH was 3.98?? I expected the pH to be higher than my mash target of 5.4 since the grain would surely drop the pH. I was not comfortable adding the 52mls so I slowly added acid until I hit about 5.8 pH.

As these 2 paragraphs appear to contradict one another I am not quite sure what you did so I'll have to limit my comments to generalities.

In making a beer you have to overcome the alkalinity (if any) in the water and the alkalinity in the mash (which can also be very low or even negative) and clearly you do that by adding acid to the water. As you are adding enough acid for the water (calculated as 90% of the alkalinity) and the grain you will clearly shoot past the alkalinity endpoint (pH 4.5) when adding to just the water. Now if you dump that water onto the grain (or dump the grain into the water) things don't happen instantaneously. For the first few seconds you have grain in acid water and a pH meter will show exactly that - acid water. As time passes the water soaks into and reacts with the interior of the grain particles and protons are absorbed. The pH goes up. It can take 30 minutes or more for things to settle out.

Is it normal for the pre-mash water to have such a low starting pH before heating and dough-in?

When acid has been added to the brewing liquor, yes.

 

[Sudz]

Sorry about the inconsistency in my rambling.

Your response confirmed what I hoped I was seeing. I guess the grain effects are just more pronounced than I expected.

Excellent response and help from you and the forum.

Thanks, Sudz