Final beer pH in Ales. Manipulation, factors effecting it etc....

[RKi]

I've been reading a lot about final beer pH lately, and all the way through the brewing progress for that matter.

It seems to me that a final beer pH of 4.3-4.5 is generally considered optimal, in terms of both flavour and microbial stability. This is for ales, not lagers (i believe 4.2-4.6 is normal for them) and of course not sour beers. From reading it seems that a lot of Sierra Nevada ales finish around 4.4, and from research i carried out, i found that almost all of a lot of top UK craft brewers ales finish in the 4.3-4.5 range.

Recently i brewed a Stout which i was unhappy with, and the final pH of that beer turned out to be 4.05, which i think is WAY too low. I know Guinness finishes around 3.9, but i consider than an anomaly generally.

Basically what i'm wondering is:

* Would an overly acidic grist ( I was way too heavy on the roasted malts) result in a lower final beer pH?

* It seems that aggressive fermentation results in lower final beer pH's. For some reason i find that my dark beers ferment far more vigorously than my pale ones, even with the same yeast (US05). Do others find this also?

* Does anyone here adjust their final beer pH with acid or bicarbonate prior to packaging? Seems like it could be a beer saving solution when the final product is out of range.


For what its worth i always mash my pale beers in at 5.2 pH and stouts at 5.4-5.6 pH. My kettle pH always falls into a desirable range (5.0-5.3). My fermentation control could be better though, i currently let US05 free ride in a temperature controlled chamber of 18.5C (65F). I monitor the fermentation temperature very closely though and it's always within 18-21C (65-70F), which is considered optimal for this yeast.

I'm generally very happy with my pale hoppy beers, and last time i measured my heavily dry hopped IPA's pH, it came in at 4.5, which i consider pretty much perfect, considering that dry hopping generally results in a pH increase.

 

[RKi]

After thinking more about this, i think the best solution is to ferment as cool as possible in order to avoid a vigorous fermentation pushing the beer too far below 4.3 pH. Alongside a sensible Stout grist too obviously.

 

[bucketnative]

I know Guinness finishes around 3.9, but i consider than an anomaly generally.

For what it's worth, Guinness blends a soured portion of beer into their stout, so it makes sense that is south of 4 on the pH scale, yet not so low as true sours.

 

[mabrungard]

Guinness does not blend soured beer back into their stout. They mash a relatively normal pale malt and raw barley wort and then add the Guinness Flavor Extract (GFE) after the mash. GFE is just the steeped roast barley and that wort does have a low pH of around 4.5 due to their water supply having very low alkalinity. GFE has low pH, but it is not soured.

 

[Northern_Brewer]

It seems to me that a final beer pH of 4.3-4.5 is generally considered optimal, in terms of both flavour and microbial stability. This is for ales, not lagers (i believe 4.2-4.6 is normal for them) and of course not sour beers. From reading it seems that a lot of Sierra Nevada ales finish around 4.4, and from research i carried out, i found that almost all of a lot of top UK craft brewers ales finish in the 4.3-4.5 range.

Recently i brewed a Stout which i was unhappy with, and the final pH of that beer turned out to be 4.05, which i think is WAY too low.

You shouldn't, you've just been paying too much attention to US practice. British beer has a significantly lower pH than US beer or lager.
See eg Murphy's : "The acceptable range of pH for cask conditioned beers is 3·7 – 4·1 units"
Or this 1974 paper from what became BRI :
(British) ale 3.8-4.2
US ale 4.3
Dortmund 4.52
Urquell 4.67

He reckoned anything above 4.1 was much more vulnerable to bacterial infection.

 

[Northern_Brewer]

Guinness does not blend soured beer back into their stout. They mash a relatively normal pale malt and raw barley wort and then add the Guinness Flavor Extract (GFE) after the mash. GFE is just the steeped roast barley and that wort does have a low pH of around 4.5 due to their water supply having very low alkalinity. GFE has low pH, but it is not soured.

GFE (formerly Concentrated Mature Beer) is a dehydrated wort exported for overseas production of FES, 2% is added to flavour sorghum wort or whatever the local brewery is using.

There's evidence from a former head brewer that in the mid-20th century they were adding very acid OBS (Old Beer Storage) among other things to Draught Guinness, but per Roger Protz they seem to have replaced that with a pasteurised wort that's "artificially" soured with bacteria - so sauergut in effect.

 

[RKi]

I tend to brew US style beers with US yeasts 95% of the time :]

Hypothetically, can you manipulate final beer pH with fermentation temperature?

i.e If i brew a beer and ferment it at 19C and it finishes at 4.20, i could brew it again and ferment it at 18C to hopefully finish at a higher pH?

It's not something i've thought about until now to be honest.