Yeast and a Preferred pH Point

[VikeMan]

In a thread on the beginner's forum, the following statement was made, in the context of extract brewing:

"For what it's worth the pH of your water is completely irrelevant - the yeast will work the pH to their preferred point in no time at all, and the malt extract combined with your water will be providing adequate buffering."

The ensuing discussion risked derailing the topic, so I'm starting this thread.

Does anyone have any authoritatively sourced information that indicates that (sacch) yeast take the pH of wort/beer quickly down to a specifically preferred point and stop there? Note: I'm not asking if yeast decrease the pH. I know they do. I'm asking about some sort of "biological imperative" specific target pH (one that confers some advantage to the yeast) that they are able to quickly hit (regardless of wort characteristics), and then stop. If this is true, there ought to be at least one peer reviewed reference out there that says exactly that. In many years of reading, I haven't come across something like that. But I'm happy to learn something new. TIA.

@eric19312
@Vale71
@Qhrumphf
@tbaldwin000
@doug293cz

 

[marc1]

A few of us could informally test this with leftover wort from brew day. The amount of beer necessary for a pH test is small. I could empty my counterflow into a mason jar instead of down the drain, then split it into 2 or 3 small jars - one with some baking soda added to increase pH, one with some lactic acid to decrease, and one "regular". Test starting pH. Pitch the same amount of yeast to all 3 and leave on the counter with loose lids. In a couple of weeks, test the final pH.

If they do not end up with similar (exact same? we should pre-specify an acceptable +/-) pHs, then the statement above is false.
Data points from several different yeast/wort grist combinations will help flesh out the results.

Edit:
Re-reading the above, it seems to be talking about water pH, which doesn't really have anything to do with the yeast. If it was wort pH there'd be a good test we could do, but water pH on its own (without other information/controlled values) is not very meaningful.

 

[doug293cz]

You rang? While I appreciate the implication that I have expertise in everything, it simply isn't true (no matter how much I want my wife to believe that I do.) This is one area where I am not an expert, and haven't even studied much.

I do agree with the triggering statement, that water pH is pretty much irrelevant when extract brewing (and also all grain brewing.) What might be important for extract (and definitely is for all grain) is the alkalinity (or buffering power) of the water, which determines how much "work" it takes to shift the pH from the starting point.

That's all I got.

Brew on

 

[eric19312]

https://blog.hannainst.com/ph__brewing_beer_testing
good reading here

 

[Qhrumphf]

Higher starting wort pH means longer lag phase as the yeast have to drop that pH.

To that extent, the alkalinity of the water probably still matters. But in any brewing, water pH is pretty irrelevant- its always the alkalinity that matters.

As far as "target" pH, gonna vary by yeast strain/condition and other wort factors (gravity, hopping, etc). 4-4.5 being a normal range. But a British yeast might routinely land 3.9-4.0 where a lager yeast might stop at 4.4-4.5. Most big beers don't seem to drop as far. I don't have a source for this, but my guess is higher gravity wort having more buffering capacity keeping the yeast from dropping pH as far. Dry hopping in particular also raises pH.

 

[day_trippr]

Gotta love "The Summoning"