Originally Posted by menschmaschine
But when you're taking a beer that already has a relatively low pH, the effect of carbonic acid could exacerbate sourness. Just thinking out loud here.
I realize this an older thread, but I've been wondering the same thing. For most of this season, I've been targeting a mash pH at room temp of 5.2 to 5.3. It dawned on me several weeks ago that perhaps this is too low -- that maybe I should be aiming for a mash pH of 5.4-5.5 at room temp in order to (maybe) have slightly rounder, fuller flavors.
The finished pH (out of the fermenter at bottling time) is always around 4.01 to 4.4 (4.4 for higher alcohol styles -- Scotch Ales, Winter Warmers, etc.). I ferment cool -- Safale 05 @ 60F or 62F for 7 days, then a slow ramp to 70F for 1-2 weeks. (I understand that cool fermentations can also drop the finished pH.)
Out of the fermenter -- at bottling time -- the beers taste fine -- no off tastes, no sourness. I add the normal amount of priming sugar at bottling -- and out of the bottle after a week (not enough to carbonate fully, I realize) they taste pretty good -- round, good malt, nice hop character, etc.
However, after about 4-5 weeks -- essentially at the month mark -- when I know the bottles are fully conditioned, the taste is still pretty good but in each of my 5.2-5.3 mash pH batches, I taste a very light -- very faint -- but distinct sourness. Hard to explain: it's not *quite* citric tart, and it's not an "off" sourness -- it's more like a direction that the malt has taken (hops still pop for the styles in which I expect the hops to pop). I don't think it's oxidation -- no cardboard tastes, no band-aid tastes, etc. In other words, the beers are still pretty good. Folks who drink them say they're great -- so I at least know other folks aren't thinking "sour" when they drink them. So far, no one who has had one has said, "This is sour." But I detect the taste -- and it's distinct across all styles.
It's not infection -- no bottle bombs, no green apple sourness -- and the beers themselves look wonderful: crystal clear, not at all cloudy, bright as any off the shelf beer.
I've got several batches of the same beers in various stages of fermentation where I've increased the mash pH to 5.4 to 5.5 (I use a pH meter I calibrate a few minutes before I start brewing for the day each day. The meter itself is new -- less then three months old -- and is always stored in solution, etc. etc.) so I'm hoping to be able to tell a difference between these new batches and the old batches.
At any rate, the thing that I'm wondering about is the carbonic acid -- if it can increase the sourness perceptibly when the pH is already low. (These are all ales, BTW -- in the brown/amber/black range -- not that color makes a difference, but I tend to like malty beers with a distinct but not overpowering hop presence.)
Finally, the beers are not at all over-carbonated. I pop the caps off beers conditioning for 1 month or so -- stored in my basement -- and i get a normal amount of fizz with a solid pour --a good, solid, tight head of bubbles -- maybe an inch or so -- in a glass. No gushers, no slowly creeping carbonation out of the bottles (signs I've seen previously with infected beers). Carbonation head atop the beer thins as I drink, but it's still there (albeit very thin) as I drink the last sips.
Is it worth decreasing the priming sugar slightly? Increasing the mash pH as I've done?
I know I have to experiment -- and I am -- but I'm looking for any additional comments on the effect of carbonic acid and taste perception on finished beers.