Side affects of, potentially, low boil pH?

I brewed a pale ale today. My mash pH was a tad lower than I'd wanted, at 5.29, but I was fine with it (I'll just add 1ml of lactic acid next time, instead of 2.). Anyways, the potential problem I ran in to was me not thinking. I used Poland Springs water for my water, including the sparge. The alkalnity, based on reports I've seen online, and a kH test kit I have, is about 20 as CaCO3. Stupidly I added 2ml of lactic acid to the sparge water (I should have just left it alone.). I'm not sure what the pH of the sparge water was, but I'd imagine it was pretty low, considering the low alkalinity. However, I'm also thinking there would have been basically no alkalnity left in the water after the acid was added, and therefore the pH of the grain bed, since the the grain bed acts as its own buffer, would have prevented much of or most of any pH change from the residual acid. I know a lower boil pH can lower hop utilization. Can anyone think of any other problems I might run in to if the boil pH was too low? Does anyone know if it's likely that the finished pH of the beer will end up too low?

Adding 2 ml of 88% lactic acid to 5 gallons of water with alkalinity of 20 and pH 7 will lower the pH of that water to approximately 3.77. That is pretty low. The alkalinity would actually be negative (-22 ppm as CaCO3 if the defining end point for alkalinity is chosen as 4.3). Yes, the grain has some buffering capacity but just as sparging washes out sugars it washes out the buffering substances. It is quite probable that kettle pH was too low. It is true that hops isomerization is lowered at lower pH but I can't think off hand of any other problems in the kettle. I suppose one could argue that normal (5 - 5.2) kettle pH is closer to the isoelectric pH's of the proteins and so lower pH would result in poorer break formation. I'd be more concerned about the yeast in the fermenter. They have the ability to regulate pH down in order to make it hard for bacteria to compete but I don't know about up. Certainly overly low wort pH would change their metabolism and thus the way the beer tastes. I'd go measure the pH of the fermenting beer right now. If it is below 4.3 I'd start tasting the beer fairly frequently to see if you want to keep it. Might turn out OK, might not.

ajdelange said:

Adding 2 ml of 88% lactic acid to 5 gallons of water with alkalinity of 20 will lower the pH of that water to approximately 3.77. That is pretty low. The alkalinity would actually be negative (-22 ppm as CaCO3 if the defining end point for alkalinity is chosen as 4.3). Yes, the grain has some buffering capacity but just as sparging washes out sugars it washes out the buffering substances. It is quite probable that kettle pH was too low. It is true that hops isomerization is lowered at lower pH but I can't think off hand of any other problems in the kettle. I suppose one could argue that normal (5 - 5.2) kettle pH is closer to the isoelectric pH's of the proteins and so lower pH would result in poorer break formation. I'd be more concerned about the yeast in the fermenter. They have the ability to regulate pH down in order to make it hard for bacteria to compete but I don't know about up. Certainly overly low wort pH would change their metabolism and thus the way the beer tastes. I'd go measure the pH of the fermenting beer right now. If it is below 4.3 I'd start tasting the beer fairly frequently to see if you want to keep it. Might turn out OK, might not.

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Huh, well, this is odd. The krausen is already starting to form after about 8 hours (with a decent number of bubbles). I just measured the pH. It was 4.85. That seems like it might make sense, considering that fermentation is approaching low krausen. I added the 2ml to my sparge water before I heated it. Would that have an effect? I only actually had 3.75 gallons of sparge water, as I did a thin (1.9 quarts / lb) mash, and did a thin non-boiling-decoction for mash out. Perhaps it was the gypsum that I'd accidentally added to the kettle before I had done the decoction (I meant for it to be a boil kettle addition only.)?

De Clerck warns that running the mash pH too low can solublize proteins into the wort from the mash. That might be a consequence here. I suppose that means that the beer clarity might suffer, but I don't know that for sure.

Sorry to hear of the mistake with the Poland Springs water. It is very low alkalinity and didn't need acidification as you've deduced. I've been recommending that acidification is not needed if the alkalinity is less than 25 ppm as CaCO3, but I see that De Clerck says that its not needed when the alkalinity is less than 1 mval (50 ppm as CaCO3). I seem to be a little too conservative!

I don't think it's odd. As you noted the malt does have buffering capacity and while it is true that sparging does wash that out it is only at the end that the sparge water is hitting unbuffered mash. So you got lucky. Much or some or enough of that extra lactic acid got 'neutralized'. Your pH going into the fermentor may have been below 5 but it wasn't below 4.85. Your yeasts didn't have as much to do to establish the pH they like and so the beer may taste a little different but I'd say you got lucky and should count your blessings.

We shall see, I suppose. It seems it might not have gotten wicked low (perhaps since I batch sparge?), since it was only pulled down to 4.85 by the time the beer reached low krausen? Then again, I don't know how fast the yeast pull the pH down normally.

EDIT: This post was in response to Martin.

Also, Kai quotes Brewing Techniques as stating that the iso-electric point for the wort proteins is around 4.9, so coagulation is optimized. Would that not potentially lead to better clarity?

How fast the pH drops depends on the yeast, the beer and the pitch. In the last beer I did (a barley wine) the pH was 5.08 going into the fermentor and 4.82 6 hours later. In the beer before that (stout) 5.09 going into the fermentor, 4.79 12 hrs after that, 4.64 24 hrs after that. The beer before that (Helles) was 5.18 in the fermenter, 5.07 8 hrs later 4.91 9 hrs after that 4.78 8 hrs later than that 4.59 24 hrs after that. So there is a pretty swift drop after a good pitch followed by a slower rate for the next couple of days. A lot of people don't think of this as a good use for their pH meters but when you see a pH drop of 0.2 or better withing the first 6 hrs or so of pitching (usually before you see physical signs of fermentation) you know that your fermentation is going to be a healthy one (barring a sudden drop in temperature which drops the yeast or some such disaster).

ajdelange said:

How fast the pH drops depends on the yeast, the beer and the pitch. In the last beer I did (a barley wine) the pH was 5.08 going into the fermentor and 4.82 6 hours later. In the beer before that (stout) 5.09 going into the fermentor, 4.79 12 hrs after that, 4.64 24 hrs after that. The beer before that (Helles) was 5.18 in the fermenter, 5.07 8 hrs later 4.91 9 hrs after that 4.78 8 hrs later than that 4.59 24 hrs after that. So there is a pretty swift drop after a good pitch followed by a slower rate for the next couple of days. A lot of people don't think of this as a good use for their pH meters but when you see a pH drop of 0.2 or better withing the first 6 hrs or so of pitching (usually before you see physical signs of fermentation) you know that your fermentation is going to be a healthy one (barring a sudden drop in temperature which drops the yeast or some such disaster).

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Cool, thanks for the info. I guess I won't worry about the beer. This was 2 week old tube of White Labs San Diego Super Yeast in a 1 liter stir-plate starter (on a 1.055 beer). I used pure O2 in the wort. I have it in my chest freezer (with heater inside) keeping it at 68 degrees.