Final beer PH too low

[Eamonn]

Hi - trying to solve a strange problem thas plagued my beers for a long time, rendering them stale tasting, same-ish regardless of recipe, but not noticeably infected or anything obvious like that. I've just found something that may be a clue.

In short: Mash PH treated with acid malt or lactic acid to get to about 5.3-5.4. Everything seems good until the clean looking and healthy fermentation is complete. Beer looks ok, but tastes and smells dull and a little paint stripper like. And a little more bitter than it should be. However, the final beer PH is around 3.8, whcih seems like a huge drop. My Milwaukee meter has been calibrated with 4 and 7 buffers, so I can't blame the meter. I've used various beer recipes and different water recipes, yeasts, some with spring water, some RO and salts, etc. Mainly pale beers, but same problem.

My last beer was a hefe with wyeast 3638, starter smelt great, RO water + 0.8tsp of both CaCl and CaSO4, mash PH 5.35, wort stability test was a success (1 week, no spontaneous ferment), but unfortunately there is no hefe aroma in final beer which had a PH of 3.8 - just dull, with a hollow, slightly bitter tang. Very weird.

Is the large PH drop a clue to something?

Eamonn

[BarefootLion]

I believe the pH of finished beer is somewhere around that range, high 3's to low 4's IIRC. Wheat tends to make a beer more tart, so I would wheat beer to be even lower.

What about recipe formulation? Have you tried someone elses recipe or do you write your own?
You're using RO water that you are building back up for every batch, maybe one of our water chemists can jump on those numbers.

[mabrungard]

A final beer pH of 3.8 is too low. A final beer pH in the low to mid 4's is more typical.

You've mentioned the mash pH has been fine. What are you doing with your sparging water? If you're starting with a RO water for sparging, you probably don't need to perform any acidification of the sparging water. If the starting water has high alkalinity, then you would probably need to acidify the sparging water to avoid tannin extraction. If the sparging water is being over acidified, that might be a source of the extra acidity in the finished beer. Since there was a mention that RO water is sometimes used for the mashing, there is little alkalinity in the mash water to help buffer any excess acidity.

If the sparging water is not the problem, I would revise my mashing pH target up a tenth or two and see what the effect is.

[DBear]

THe RO water I use has a pH of 8 and I adjust for mashing.
Is sparge pH over 6 even an issue when batch sparging?

[Eamonn]

A final beer pH of 3.8 is too low. A final beer pH in the low to mid 4's is more typical.

You've mentioned the mash pH has been fine. What are you doing with your sparging water? If you're starting with a RO water for sparging, you probably don't need to perform any acidification of the sparging water. If the starting water has high alkalinity, then you would probably need to acidify the sparging water to avoid tannin extraction. If the sparging water is being over acidified, that might be a source of the extra acidity in the finished beer. Since there was a mention that RO water is sometimes used for the mashing, there is little alkalinity in the mash water to help buffer any excess acidity.

If the sparging water is not the problem, I would revise my mashing pH target up a tenth or two and see what the effect is.

Thanks for the comments thus far.

I use untreated RO or soft bottled water for sparging. I only treat the mash, which is about 4L:1kg liquor to grist ratio. I batch sparge or use BIAB with a topup.

I've just got no idea why the PH is getting dragged so low... What sort of reactions can cause drop of about 1.5-1.6 PH ??? I use sodium percarb for soaking / cleaning, and starsan. Both are to the correct concentrations.

I do not want to waste my time on another brew until I have a good threory as to what could be causing this.

[ajdelange]

If your mash pH is OK pH at other phases in the process should fall into place. Thus the first thing to do is check pH at several points (dough in, each rest, every decoction, kettle at start of boil, going into fermenter). Knockout pH should be close to 5 and pH should drop in the fermenter to 4.4 - 4.6 for lagers and 4.2 - 4.5 for ales. The only beer that drop below 4 are lambics, wits etc. and, of course, that suggests that lactic or other infection is the source of your problem especially given your mention of strange aromas.

[craigevo]

AJ - care to share why ales should end up a bit lower than lagers ?

Is this the desired range, or is it just a function of the fermentation/yeast.

I mean, should we aim to get the wort ph a bit lower going into the fermenter for ales compared to lager- or does ale yeast just drop the ph more than lager yeast and the ph going into the fermenter should be the roughly the same ?

I think I may have asked this question before somewhere, but cannot remember the answer now.

[ajdelange]

I would if I could but I don't have an answer to that one. I do have a vaugue recollection of having seen something on this subject recently I think probably in the White/Strong yeast book but don't remember what it was and am not at home so can't check. Perhaps lager strains living under cold conditions do not need to produce as low a pH in order to compete.

German brewing texts seem to recommend a higher range of allowable mash pH than British brewing texts.