I'm pretty sure I just had my first oxidized beer. I brewed a harvest ale about a month ago and kegged it about 2 weeks ago. After that it tasted great, smooth and citrusy. Last weekend I finished building my keezer and hooked my kegs up to it. While I am always very diligent about purging the O2 out of my kegs, I didn't think to purge the O2 out of the new gas lines and manifold. After hooking everything up I just turned on the CO2, opened the valves on the manifold and left it. After a few days it tasted completely different. A bit more astringent and musty. Left it another 2 days and its even worse. No way to save it?
To me, musty sounds like more like mold or other infection than oxidized. Some yeasts can produce musty flavors/aromas, but most brewing strains don't. Astringent doesn't really sound like oxidized either. Can you describe more about (or use other words for) what you're tasting? If it is oxidized, I don't think there's a cure at this point.
Not sure I understand . . . the process of burbing your keg will clear your lines. The amount of air in your gas line before pressurizing is a small quantity, if you pressurized and released the CO2 a couple of times from your keg you should have little to no O2 hanging around. The detective in me suspects your oxidation is from another source. I've had oxidized beer before and to the best of my knowledge it's a goner.
I pressurized and burped it when I originally carbed it, but once I hooked it up to my new manifold and gas lines I didn't purge it, I just turned on the co2 and left it. I always hear about wet cardboard being the taste of oxidized beer and that was the first thought that came to my head when I drank it.
I am not aware of any way to reverse oxidation, sorry. It's possible that the method you described would produce oxidation--it's always good to pressurize an purge a couple times with the beer in the keg to make sure it's all C02 (or as close as is reasonably possible) before starting carbonation. But the off flavors you describe don't necessarily sound like oxidation. Either way, this batch is probably lost. Ah well. We all have a drain pour now and again. The bright side is it's an excuse to get brewing.
