Ok, this is definitely a 'wait and see if the off-flavors go away" thing, but I'm curious if anyone else has had this happen to them.
I will start by saying I brewed an ordinary bitter and dunkelweizen four weeks ago, and an IPA three weeks ago. The bitter was about average IBUs for the the style (about 30), the dunkel was about 12, and the IPA was low for the style (45). I dry hopped the hell out of the IPA. I recently started kegging as well, and I have only kegged on batch of beer prior to these three.
I hit 80% efficiency on the bitter, 55% on the dunkel (stuck sparge, I only later learned about using rice hulls in the mash) and 75% on the IPA. They all spent about 5 days in the primary and 10 days in the secondary and reached pretty good levels of attenuation.
As I kegged the beers, I tasted them all, and the bitter turned out nice and balanced, the dunkel was weak but it was alright, and the IPA was just full of hop flavor and aroma, and quite low on bitterness. To age the kegs, I put the beer under a small amount of pressure (5 psi) and let the bitter sit for two weeks, the IPA one week. At the one week mark, the bitter tasted slightly better than when I kegged it, which was pretty good. The IPA only stayed in the keg for one week since I like the style young. The dunkel also aged two weeks in the keg.
Now, two days ago I force carbonated all three beers. I tasted them today after they carbonated, and the bitter and IPA had a totally overpowering bitter taste to them. I'm not sure I could call it astringent, but maybe. I cannot describe how much these beers changed right after they were carbonated, as I was tasting them as they aged in the keg.
Has anyone else had this happen? I'm sure the flavor will mellow with time, but I've never heard of this problem before, and this same thing happened to the brown ale I brewed previously and carbonated with the same CO2 regulator and tank.
Strangely enough, the dunkel was on a new, second regulator that comes before the regulator that the other two were attached. It has no such off flavors, but then again, it also has much lower IBUs. The brown ale that this happened to previously had an IBU rating of 22, which is not far off from the dunkel.
As much as I hate to be the chef blaming his ingredients, is it possible that a C02 regulator could be imparting strange flavors to my beer?