Adjusting Final pH After Fermentation

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Bobo1898

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How do you adjust the pH in the keg, post fermentation. Is it as simple as adding the acid directly to the keg?

Is there a way to calculate how much acid I would need, to lower the pH, with the volume I have?

What type of acid would you recommend using? I typically use lactic acid in the mash but am wondering if this would be an issue with finished beer.
 

3 Dawg Night

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Honest question, because I don't know the answer: why would you want to adjust pH after fermentation?

I've always heard that 1 ml/gal is the taste threshold for lactic acid, so if you end up needing more than that, you should probably go with something like phosphoric acid.
 
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Bobo1898

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The most critical stage of pH is obviously the mash, but it was explained to me that there is value in understanding final pH.

From what I understand, various styles have a range of what that final pH should be. I think hops also can increase pH so for heavily hopped styles, it sounds like it's possible that the yeast doesn't drop the pH enough during fermentation to be within range. A brewer had recommended to my homebrew club that you can adjust this post fermentation or get ahead of it by adjusting post boil. He actually encouraged to adjust the final pH with acid.

I've always heard that 1 ml/gal is the taste threshold for lactic acid, so if you end up needing more than that, you should probably go with something like phosphoric acid.
I don't imagine using that much for adjusting the final pH, especially if mash water and sparge water has been adjusted. But if this is an overall rule of thumb totalling the entire process including mash, sparge and final...then phosphoric may be a better choice.

I wasn't getting much of a response on this question so I guess I pose it again. Would there be a simple calculator I can use to calculate how much of an addition of acid I'm adding with the current volume I have?
 

marc1

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The most critical stage of pH is obviously the mash, but it was explained to me that there is value in understanding final pH.

From what I understand, various styles have a range of what that final pH should be. I think hops also can increase pH so for heavily hopped styles, it sounds like it's possible that the yeast doesn't drop the pH enough during fermentation to be within range. A brewer had recommended to my homebrew club that you can adjust this post fermentation or get ahead of it by adjusting post boil. He actually encouraged to adjust the final pH with acid.



I don't imagine using that much for adjusting the final pH, especially if mash water and sparge water has been adjusted. But if this is an overall rule of thumb totalling the entire process including mash, sparge and final...then phosphoric may be a better choice.

I wasn't getting much of a response on this question so I guess I pose it again. Would there be a simple calculator I can use to calculate how much of an addition of acid I'm adding with the current volume I have?
There's a calculator in Mash Made Easy that calculates boil pH adjustment, so you can add acid before or at the end of the boil.
 

Silver_Is_Money

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There's a calculator in Mash Made Easy that calculates boil pH adjustment, so you can add acid before or at the end of the boil.
Since MME relies upon a scaled/variable measure of anticipated/requisite pH drop across the boil as part of its math model, it can not be validly used exclusively post boil (as the boil drop math modeling will work against you). To attempt to use MME as the OP intends would be a mistake sort of akin to attempting to apply the full application of Kolbach's pH drop math model to the mash exclusively (as had been done for decades, and is still to this day being actively done by some), when he made it clear (in German which was obviously overlooked to outright ignored) that his work in modeling the pH drop due to Ca++ and Mg++ mineralization was measured across both mash and boil (and wherein he likewise was anticipating as well as accounting for some measure of the requisite drop in pH to be due to the boil and not merely due to Ca++ and/or Mg++).
 

marc1

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Since MME relies upon a scaled/variable measure of anticipated/requisite pH drop across the boil as part of its math model, it can not be validly used exclusively post boil (as the boil drop math modeling will work against you). To attempt to use MME as the OP intends would be a mistake sort of akin to attempting to apply the full application of Kolbach's pH drop math model to the mash exclusively (as had been done for decades, and is still to this day being actively done by some), when he made it clear (in German which was obviously overlooked to outright ignored) that his work in modeling the pH drop due to Ca++ and Mg++ mineralization was measured across both mash and boil (and wherein he likewise was anticipating as well as accounting for some measure of the requisite drop in pH to be due to the boil and not merely due to Ca++ and/or Mg++).
I was not very clear.

OP mentioned adjusting post-boil, my post was to let them know that there was an option for boil adjustment.
 

mabrungard

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The buffering system in beer is not the same as wort. You can't rely on pre or post boil wort calculations to predict acid additions. I suggest sequentially dosing a glass of beer with acid until you find the level that makes it taste better to you. Then scale the acid addition up to fit your batch size.
 

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From Martin Brungard's excellent website:

If you have a beer with flavor or perception that is a little dull or flabby, dosing the beer with an acid can make a significant difference. While a universal acid dose can’t be prescribed, you can conduct taste tests in a glass of the beer to find a dose that pleases you without being too acidic. A dropper or pipette is recommended to enable you to measure your dose. Use a glass large enough so that a single drop of your acid won’t instantly put the beer over the limit. Give the beer a good stir and taste. Once you’ve found a pleasing dose, scale that up and add to the kegged beer.

Similar taste testing can be performed when dealing with a dark and roasty beer that has an overly sharp or harsh bite to it. It may be possible to take the edge off that beer by raising its pH with either lime or baking soda. Again, measure out a small amount of either mineral (say 0.1 gram in a pint of beer) and stir it in and taste the beer. If the taste improves, try similar doses to see if it further improves the beer. Scale it up and dose your kegged beer if you find a pleasing dose.

Note that these recommendations don’t require the use of a pH meter, but measuring beer pH before and after adjustment is a good idea. There is no guarantee that pH adjustment will correct a disappointing beer, but consider this a tool for tuning your beers to your preference!


Source:
 
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Bobo1898

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Thanks for the responses, this is very helpful.

I will give a try with dosing samples.
 

crazyjake19

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I always measure my pH throughout the batch of beer from mash to glass, though I never make any pH alterations post-fermentation. It absolutely does affect the perceived flavor and body of the finished beer, though I just use the information to plan an adjust on the next batch.
 
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