Mechanics of adjusting mash pH

[LovesIPA]

Now that I have a pH meter, a question has popped up in my mind. You're supposed to measure mash pH at room temperature, 15 minutes into the mash so the pH will stabilize - is this correct?

Even if you can cool a sample to room temp in 5 minutes, you're still 20 minutes into the mash. Isn't it too late to make any adjustments? If the mash pH is 5.6 and I need to add X amount of acid, it seems like 20 minutes in is too far in to do any good.

Is it just something that I need to get good at predicting and just have it "work out" with a lot of experience?

 

[mabrungard]

If your pH is within a tenth or so, then its not really a big deal. But if its way off, then there could be some effects on the beer. Some brewers are good at predicting. I know I have gotten pretty good at it!

 

[LovesIPA]

Let's just say I test my pH and it's 5.6. If my target pH was 5.2, is it even worth adjusting? Or should I take it as a lesson learned and try to mash the grain bill again with some acid?

Someday I hope to get pretty good at estimating the pH - but I'm not quite there yet.

 

[mtnagel]

I've read that you can measure at 5 mins into the mash and then adjust if necessary so at most you are 10 minutes into the mash and it would still be beneficial to adjust at that point.

In the beginning, I didn't trust the spreadsheets, so that's what I did. I have since read that Martin has said you should add the acid before heating up your strike water so the last beer I made, I trusted Brun Water and the pH was at target when I tested it 5-10 mins into the mash. The beer before that the pH was high, but I measured my water wrong and added too much water. So I guessed on how much acid to add and hit it after that.

 

[ajdelange]

Now that I have a pH meter, a question has popped up in my mind. You're supposed to measure mash pH at room temperature, 15 minutes into the mash so the pH will stabilize - is this correct?

Yes, but with experience you will learn to be able to lead your readings and figure out about where things are going to settle after a couple of minutes.

Even if you can cool a sample to room temp in 5 minutes, you're still 20 minutes into the mash. Isn't it too late to make any adjustments? If the mash pH is 5.6 and I need to add X amount of acid, it seems like 20 minutes in is too far in to do any good.

Its never too late unless your pH excursion is so dramatic that the enzymes get denatured but that is most unlikely to happen. It is, of course, better to not have to make corrections in the mash. Many have wound up chasing their tails - over correcting first in one direction and then the other.

Is it just something that I need to get good at predicting and just have it "work out" with a lot of experience?

That will, we hope, happen eventually but before it does it is wise to make a small test mash and check its pH. If it is way off the main mash will be too and you can revise your recipe to bring it closer to where it should be.

 

[pjj2ba]

I have never checked my mash pH with a pH meter. Before I got my meter I would check it with pH strips. I've got a good feel for my water, it has low alkalinity after treating it, and I brew mostly lighter beers. I know that if I adjust the pH down to 5.4 after lime treatment (with the help of phosphoric acid and the pH meter), that with my simple grain bills the pH should be right where I want it to be. I get great conversion, so I don't bother checking the pH after mashing in.

I monitor conversion with a refractometer so I guess if it was not converting like it normally does, I might check it's pH then, but that hasn't happened.

I guess the take home lesson is to know the buffering capacity (alkalinity) of your water

 

[ajdelange]

I guess the take home lesson is to know the buffering capacity (alkalinity) of your water

That's part I
Part II is to know the buffering capacities and DI pH's of your malts.

 

[pjj2ba]

That's part I
Part II is to know the buffering capacities and DI pH's of your malts.

Correct! I brew almost exclusively with just base malts and they don't have the impact on pH (away from my target pH) that the specialty malts do

 

[ajdelange]

In base malt mostly mashes given that the buffering capacities of base malts are about the same the big swinger is DI mash pH. Wyermann has two Pilsner malts. The DI mash pH of one is about 5.6 and of the other 5.8. Depending on which you use and how much other malt is in there you will see a mash pH difference of almost 0.2.

 

[dlester]

I use RO water, which is typical in the high 5's on pH. Moving the pH requires maybe a drop of 25% acid solution if I adjust prior to mashing. However, during mashing takes a lot more. I figured that the buffering capacity of the grain is the culprit as noted by several of you. I therefore will only check after the grains have been introduced to the water. I also add my brewing salts during the Mash.

Regarding the temperature, my pH meter adjusts to the temp. I never thought of temperature being a hurdle to get a good reading. Am I wrong? Either way, I am reaching about 82% efficiency on my mash at 60 minutes, and higher if I mash 90 minutes.


Cheers,

 

[ajdelange]

RO water has very low alkalinity (about 2.5 ppm as CaCO3 to pH 4.5 - even less to mash pH) which is why it takes only a smidgeon of acid to move its pH appreciably. The malts, OTOH, have akalinities of around 35 mEq/pH-kg.