Huge PH drop after fermentation from around 5 to 4.2, why?

[Miles_1111]

I brewed an Imperial Stout with a Ph 5.4 at the beginning of mash, then 5.2 after mash, drop to 4.95 after boiling ( before fermentation to be precise), I think at these stages the PH are all normal ( correct ), but after 2 weeks of fermentation ( when I bottle it ) I tested the PH drop to 4.25!! It's a dramatic drop..

Has anybody run into situation like this? Why has this happenend? Thanks.

 

[RPh_Guy]

Yeast lower the pH. Totally normal and expected.
Final pH typically ranges from 4.0-4.5.

 

[Qhrumphf]

That is perfectly normal. The yeast drop the pH, and the level is dependent on a myriad of factors, a major one being the yeast strain (some drive pH lower than others). 4.2-4.3 is a good finishing pH. Anywhere from 4.0-4.5 is good and typical. Above 4.5 gets dicey from a stability standpoint (yeast health problems can cause it, as can dry hopping), and some yeasts will push it down into the upper 3's as well, which is fine.

 

[Robert65]

That's just what you want! You should hope that pH will drop to the 4.2 range in the first hours of fermentation, certainly the first day. This is one of the things yeast does, and it protects your beer from infection, among many other desirable other things. You also do want the post boil/pre fermentation pH around 5.0, because that's where Irish moss type finings need to be (they don't work much below or above) but it's also low enough to ensure that the yeast will in fact be able to get it down around 4.2 quickly enough. (Some beers require adjusting the post boil wort with acid, since the ideal pH for the start of the boil is 5.4) So, you got everything working right. Chill with a beer you made earlier.

 

[Qhrumphf]

That's just what you want! You should hope that pH will drop to the 4.2 range in the first hours of fermentation, certainly the first day. This is one of the things yeast does, and it protects your beer from infection, among many other desirable other things. You also do want the post boil/pre fermentation pH around 5.0, because that's where Irish moss type finings need to be (they don't work much below or above) but it's also low enough to ensure that the yeast will in fact be able to get it down around 4.2 quickly enough. (Some beers require adjusting the post boil wort with acid, since the ideal pH for the start of the boil is 5.4) So, you got everything working right. Chill with a beer you made earlier.

A representative example of what I normally see:

KO wort: 13P and 5.1 pH
Day 1: 11P, 4.8 pH
Day 2: 6P, 4.3 pH
Day 3: 3.5P, 4.1 pH
Day 4: 3P, 4.1 pH
Day 5: 2.5P, 4.2 pH

After dry hopping, could climb back to 4.4-4.5.

So yes, it drops pretty quickly, but apart from a few very strong acidifying yeasts (British and Belgian typically), I don't see many yeasts that drop it from lower 5s to lower 4s in one day (but usually by day 2). Conan does it (often hitting the upper 3s by day two and climbing back to around 3.95-4.0 during conditioning).

 

[Robert65]

A representative example of what I normally see:

KO wort: 13P and 5.1 pH
Day 1: 11P, 4.8 pH
Day 2: 6P, 4.3 pH
Day 3: 3.5P, 4.1 pH
Day 4: 3P, 4.1 pH
Day 5: 2.5P, 4.2 pH

After dry hopping, could climb back to 4.4-4.5.

So yes, it drops pretty quickly, but apart from a few very strong acidifying yeasts (British and Belgian typically), I don't see many yeasts that drop it from lower 5s to lower 4s in one day (but usually by day 2). Conan does it (often hitting the upper 3s by day two and climbing back to around 3.95-4.0 during conditioning).

I'm primarily a lager brewer, so it does tend to take two days to hit the 4.2 range, but 4.5 or so in 1 day is not unusual. The timeline is of course dependent on the overall fermentation schedule. Everything happens faster with a British yeast that might finish in 60-72 hours. At any rate, insufficient pH drop is a sign of abnormal yeast performance, and it should drop more rapidly at first and then more slowly reach its end point.

 

[Northern_Brewer]

Murphy reckon commercial cask beer should end up at pH3.7-4.1 : https://www.murphyandson.co.uk/resources/technical-articles/ph-of-beer/amp/

US brewers tend to aim a touch higher.

 

[Robert65]

Murphy reckon commercial cask beer should end up at pH3.7-4.1 : https://www.murphyandson.co.uk/resources/technical-articles/ph-of-beer/amp/

US brewers tend to aim a touch higher.

Lager yeasts won't drop it as low as many ale yeasts will. 4.2-4.5 is a normal finished beer pH for lagers, though Pilsner Urquell is reportedly as high as 4.6.

 

[Miles_1111]

Yeast lower the pH. Totally normal and expected.
Final pH typically ranges from 4.0-4.5.

That might be the good range for pale beers according to Palmer's book: How to Brew, but my batch is an Imperial Stout, which should taste better with between 4.3-4.7. I think I am a bit off..

 

[Miles_1111]

That is perfectly normal. The yeast drop the pH, and the level is dependent on a myriad of factors, a major one being the yeast strain (some drive pH lower than others). 4.2-4.3 is a good finishing pH. Anywhere from 4.0-4.5 is good and typical. Above 4.5 gets dicey from a stability standpoint (yeast health problems can cause it, as can dry hopping), and some yeasts will push it down into the upper 3's as well, which is fine.

For Imperial Stout the PH I got is still a bit low I think

 

[RPh_Guy]

You cannot taste pH.

 

[bracconiere]

You cannot taste pH.

i can definitely feel it...

 

[RPh_Guy]

i can definitely feel it...

Your mouth immediately buffers the pH, so it's not pH you're tasting. Any sourness, tartness, "brightness", etc comes from tasting the acid (and its salts).

Spit some beer into a glass and test the pH. You'll see it's near neutral.

 

[Robert65]

Spit some beer into a glass and test the pH. You'll see it's near neutral.

I trust you. I'll take your word for it rather than waste one sip of beer at Christmas! ;D

 

[bracconiere]

Your mouth immediately buffers the pH, so it's not pH you're tasting. Any sourness, tartness, "brightness", etc comes from tasting the acid (and its salts).

Spit some beer into a glass and test the pH. You'll see it's near neutral.

i have used my ph meter to test my urine though, beer makes it acidic.....lol

edit: but i didn't taste it, and my meter got a thorough washing in soapy water.....and i don't know how many mols of alkali saliva has to nutrilize acids....

 

[RPh_Guy]

i have used my ph meter to test my urine though, beer makes it acidic.....lol

Does drinking lower pH beer cause a lower urine pH? I think we need you to research this for us.

 

[bracconiere]

Does drinking lower pH beer cause a lower urine pH? I think we need you to research this for us.

my ph meter is game, i'm drinking more cider recently...i could test the difference.....think the cider is 3 and the beer 4....been drinking cider all day today, i'll piss into a glass and check for you, lol

edit: well the cider isn't as bad as beer, only got 6.2 after 10 drinks, usually with beer it's it's like 3 or something forget what.....i'll keep you posted, i got a batch of amber ale almost done fermenting.....

edit #2: but i did just drink a collard green smoothie....