Ph levels and yeast viability during fermentation

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jayareo

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All -

First time with a stuck mash for me... I have controlled for temp, sugar and yeast cells (nice healthy starter). So I checked the pH and I think that this is the issue. It is 3.47, and I am reading this is much too low (too acidic). So do I need to adjust the pH and then re-pitch new yeast? Does the acidity kill yeast, or just make it lazy? If I just adjust the pH, will the yeast then re-engage?
 
All -

First time with a stuck mash for me... I have controlled for temp, sugar and yeast cells (nice healthy starter). So I checked the pH and I think that this is the issue. It is 3.47, and I am reading this is much too low (too acidic). So do I need to adjust the pH and then re-pitch new yeast? Does the acidity kill yeast, or just make it lazy? If I just adjust the pH, will the yeast then re-engage?
Do you mean a stuck fermentation? I’ve kettled soured beers down to 3.2 before reboiling and then pitching yeast and have no problems but that’s not to say that some strains don’t struggle in a low ph environment, I mean that’s exactly what starsan uses to sterilize equipment (though the ph of it is far lower that 3.4)
what was your mash ph? Did you mash at 3.47?
 
HA. yes, stuck fermentation - slip of the mind there.

I have no idea what the pH was at any other time during the process ... I borrowed a friends meter to do this reading. But really what I am after at this point is, does acidity kill yeast? Or just slow it WAY down?
 
Different yeasts handle acidic environments better than others. And different yeasts will drive the pH down further than others.

3.47 is definitely low for anything other than sour beers. There are some normal brewing strains that'll dip into the upper 3's though (meaning like 3.90 or thereabouts)

So something likely isn't right. The pH shouldn't have killed your yeast. But something isn't right that is potentially both driving the pH down AND stunting your fermentation.

I have experienced a combo of both lots of acid AND buffering capacity stunting fermentation (so the pH wasn't particularly low but the actual amount of acid added was quite high). It eventually finished but took a long long time.
 
HA. yes, stuck fermentation - slip of the mind there.

I have no idea what the pH was at any other time during the process ... I borrowed a friends meter to do this reading. But really what I am after at this point is, does acidity kill yeast? Or just slow it WAY down?
acidy will not kill your yeast at the ph it is currently at. So we need some more info to help you understand what happen so that we are better able to give you suggestions. What was your grain bill anf your water profile to start, distilled or did you build it with minerals, or is it well/tap Without a lacto strain or wild yeast/bacteria contamination, i can’t imagine a brewer yeast strain getting your ph that low given the mash was properly ph adjusted. Brewers yeast usually will only get you too 4.1-4.6 ph give or take for strain and knock out ph.

one possibility for example is if your mash ph was too low, you may have gotten very poor conversion of the starches and left the yeast with very little sugar to consume. So the more information out provide the better we can help you
 
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