But if you're not feeling the gain,
@Clint Yeastwood, then it could make sense to relax your anti-oxygen efforts. In contrast,
@Bobby_M educated his palate and got into beer competing, with considerable success. None of this means any of us is drinking "bad beer."
btw, I've largely lost interest in brewing hazy/juicy/NEIPA beers anyhow.
I'm not planning on going backward on purpose. I do enough of that unintentionally. I do try to limit O2. I try to take whatever good advice I see here. That's why I signed up.
I ferment under pressure. I use a keg full of sanitizing solution to receive fermented beer. I pump the fluid out using CO2, and then I pump beer in to replace the CO2. I don't open anything up to the air after fermentation starts. I'm probably doing about as well as most people here. But is the process perfect? If I pick at it, I can see little things that might have permitted a tiny amount of air to get in. Enough to cause a problem? Search me. All I'm saying is that it looks like there are things that could be improved.
I think I get something like 2000 ml of headspace in a filled keg, and I would guess several ml of air, or 1/5 of several ml of O2 (by volume) could get in there if I use the practices people talk about here and nothing more. So call it 1 ml. That's 0.5 parts per thousand, not million, so 500 ppm. Is that right? Someone check. That's 500,000 ppb, so somewhat higher than the 150 ppb cited above as a commercial goal. If I'm doing better than I think, by a factor of 10, I'm still at 50,000 ppb. A little high.
I have read that O2 takes a couple of months to cause off-flavors. I know that when I move beer to a serving keg, I'm agitating the yeast, and if there is anything in the beer it can still eat, it probably will, and that would presumably use up O2. Would it use up enough, fast enough, to eat whatever O2 gets in due to little things no one cautioned me about, before the O2 can do harm? No idea, but I'm smart enough to ask the question. What if I have 5 ml of O2 in the keg, and the yeast eats it in two weeks? Does that save me? Does anyone even know?
I have looked at the list of off-flavors. I think it's possible I've detected a sherry flavor in one beer, but I liked it, so I don't know what to say about that.
Somewhere I saw this list: “Any one or a combination of stale, winy/vinous, cardboard, papery, or sherry-like aromas and flavors.” Stale? Never. Winy? That's a tough one. What kind of wine? I wouldn't mind a tiny bit of resemblance to good Champagne in certain beers. Cardboard? Never. Papery? No. Sherry-like? Conceivably, but I would have to try a beer that definitely had an O2-generated sherry flavor in order to really know.
It's easy to list off-flavor descriptions, but I don't think anyone can hope to know exactly what they taste like without deliberate exposure to train the palate. How many of us have done that? Maybe I'm tasting a sherry off-flavor, or maybe this combination of yeast, malt, and hops just has a flavor that could be a little bit like sherry without being the result of O2 contamination. I think somebody out there offers a kit of samples to train people. Maybe someone here knows more.
Regarding OP, he will probably knock this keg off before two months have passed. Even if he did things badly, he will probably enjoy the beer, and he will surely improve his technique as time passes.
When I say I think people may be too worried about small amounts of O2, I don't mean that O2 doesn't hurt fermented beer. I just mean that minute amounts of O2 may not be a huge issue for most of us, who don't mind or necessarily notice small flaws and don't keep beer for long periods. I would rather have a slightly flawed glass of my beer than a perfect can of Coors.