I have a few kegs of wild ale keg conditioning. These are my first few batches doing this. Basically I ferment them in plastic with sacch then transfer over to keg with a mixed brett culture and some priming sugar. CO2 builds up and I have a sprunding valve that keeps 20 psi on the keg. Keg sits at room temp. My problem: when I pull samples every few weeks, the beer tastes kind of harsh... like carbonic acid, while the beer remains relatively uncarbed (maybe 1.0-1.5 volumes). Is this because the CO2 has not completely been dissolved into the liquid yet, is that why I am getting this carbonic acid harshness? FWIW, the beer going into the keg a few months ago tasted beautiful. No off flavors other than harsh carbonic acid-like bite. Whats going on?
Room temperature? That is your problem. 20 psi at 38F is 3.30 v/v. That is a lot of dissolved CO2. 20 psi at 65F is 1.99 v/v. That is not enough dissolved CO2. The chart ends at 65F so it might be even lower. Few things. You need to store the kegs at serving temperature and apply the correct pressure for the desired vols. You can get perfect vols if you apply the correct pressure at the correct temperature and wait 4 or 5 days. The vols will be spot on. No guessing. Even though force carbing will get your beer carbonated quickly all beers benefit from some ripening. A week of quiet conditioning helps a lot for ales and lagers really need a month or so. Warm beer tastes different than cold beer. The balance of carbonic acid bite is not the same. Cheers.
Yeah, not trying to carb right now, just condition. Keeping 20 psi at room temp to expedite Brett character development and also will cold condition for a week at 38 prior to bottling to get ~3.3 volumes. Just worried about that carbonic acid bite. Hoping it will go away when the beer is cold and then bottled.
A couple of things going on here: First there is no intermediate degree of carbon dioxide dissolving in water. Concentration yes, but once equilibrium is reached it does not "mellow out". CO2 loves to diffuse into water (beer) and will do so fairly rapidly under the conditions we force into our brew. Once it's equalized don't expect anything else to change; expect CO2 + H2O to yield H2CO3 . . . your only control is temp/press which affects final concentration. That said, I'm of the opinion your off taste is a result of temp (relatively high) and maybe whatever the Brett is contributing. Carbonic acid is not a likely suspect to cause any problem, especially at this low level. Even at high levels of carbonation you shouldn't have a concern. I regularly drink Weihenstephaner Weissbier which must be 3.5v and it's smooth as silk. Tonight, I popped a Blaugies Saison . . . the cork flew the distance of my kitchen/living room, hit the ceiling fan, and I counted two turns before the cork finally came to a rest. The resulting taste was as mild as you would ever want. My conclusion: high carbonation level does not give an unfavorable carbonic aftertaste. What I would worry about is packing your final product. You stated you have Brett and sugar in the keg, I suspect you'll struggle to know the final carb level. If you ultimately bottle carb you are starting with an unknown residual CO2 level, which makes it tough. If you keg carb, then transfer to bottles expect some difficulties getting 3.3v beer to enter a bottle and not have a lot of foam (been there, done that). The simplest approach would be to serve from a keg. I serve my Belgians from a keg at 3.0v and after a little trail and error this works okay. Pretty sure you know the Brett will continue to add a smidgen of CO2 over time, you might want the initial carb level to be slightly lower, or give consideration to cork/cage which is the old-timey method to solve a modern problem.
I am hoping more time in the keg to condition and then cold crash for a good week to dissolve all CO2 into concentration will do the trick. Gonna let the kegs condition with brett for 3+ months before I bottle, so I don't expect much additional CO2 produced in the bottle. Also, will be using counter pressure filler to reduce foaming when bottling. Also will bottle from keg that sits in ice water bath to keep the beer as cold as possible. Think this should be ok?
This is vital, if possible you want it below normal serving temp. I only bottle my Belgians when I need a few for a comp or gift and it's still tricky . . . and I'm talking 16psi/38 or ~2.9v. In my house room temp is high 70s and it's amazing how fast a chilled bottle will equalize. My technique is to put the bottles in freezer until they are sub-zero, then transfer about six at a time to a mini-cooler that is full of ice (only touch the bottles by the neck). Then have your beer gun sanitized and pre-chilled before starting. I still pour off at least half a bottle getting all the hoses, QDs, clamps, whatnots chilled. Even still I have more foam than I'd like, but at least it's caught in the mini-cooler. Counter intuitive but you'll want to boost your pressure about 1psi the night before to make up for what's lost in bottling. It is much easier if you have one person capping while the other is filling, otherwise it is a lot of stop and go. If doing something like 40 bottles I would stop about mid point and reset the high pressure, have lunch, then come back and finish. Here is a little homemade toy that I find helpful for doing odd-carbing like you are considering (all from spare parts expect gauge): Slip this on your gas post and get an idea of how excited your carbon dioxide molecules are.
