Does it have a distinct taste or is it more of a pronounced and rapid fading of original flavors?
The best description I can give is to suck on a piece of soggy cardboard or chew a sheet of paper. I found a bottle of my homebrew that was probably 8-10 years old and of course I had to try it. It was crystal clear, nicely carbonated but tasted absolutely like a wet cardboard box smells. 
eiww. well, that doesn’t sound good at all.
along, similar lines…
What do folks consider best practice for oxygenation prior to fermentation. I’ve read that an O2 tank and stone deliver the most optimal ppm. But recently with the ramp up costs of a keezer build and going all grain it may be some time before I can get that expenditure approved by the finance officer (brewmistress). By the way, the Brewmistress would like to express her gratitude for the advice of never off-gassing in her presence.
Some use tanks and stones. You can use a mixstir or shake also. I prefer agitation and then a big pitch of yeast.
Oxidation flavors can take many different forms. Wet cardboard and paper are some of the more obvious and offensive ones, but it won’t always present that way. In general, you’ll notice a dullness of flavor, where what was once bright, fresh and clean will seem muted, dusty, and bland. It can make a beer seem more caramelly sweet, or fruity, depending on what was in the beer before it was oxidized. Some take on sherry or madeira notes. I think melanoidins and maillard products tend to get those sherry notes, while acids tend to get estery. I also tend to notice the finish getting harsher and seemingly more bitter. The color can fade or at least darken in hue. It might start getting cloudy or showing flakes suspended. There are a lot of chemical compounds in beer, and all of them will oxidize. Each reacts differently. So the art is in deducing that it has happened when it shows up in so many different forms and intensities. It’s not like flipping a switch; there is a matter of degrees. For the average beer, I’d say it usually shows up as dull and more caramelly, before it starts getting obviously stale.
Very helpful comments all, thank you.
Same. I shake the hell out of my fermenters for 4-5 minutes after filling them when I pitch the yeast. Never had an issue. My last batch was OG: 1.062 and finished at 1.010.
for oxygenating wort, it depends on the yeast. Ales do fine with shaking the bejebus out of it, lagers and big beers may require more oxygen than that can deliver.
You can get little oxygen bottles with adjustable regulators at your local homebrew shop or HD or Lowes.
if you ever tapped a keg for a party and then tried to finish it the next night, that is the taste (not tapped with co2 but with the old air hand pumps. to me it is just a stale taste.
I personally use the O2 bottle and stone. Just about every homebrew store has a kit, but you have to get the O2 bottle at your local hardware store because they can’t be shipped. If you go this route, you need to be careful not to over do it. You can have too much of a good thing, promote too much yeast growth, and end up with less-than-clean beer. Just follow the directions and you will be fine.
Follow the directions on the stone or the O2 bottle?
What should I expect to spend for this handy little o2 system?
There are a couple of different kinds. Mine comes with a regulator, the stone on the end of a stainless rod, and a length of clear hose. If I recall correctly, i think that was about $30. The O2 bottle from Home Depot is about $10. The directions come with the regulator/stone kit.
If it is quick oxidation this is what I get as well. The longer it develops the more “sherry wine” like it gets. The wet cardboard is a decent analogy as well.
And I’m glad Gordon also mentioned the weird caramel taste that oxidized beers have. That’s something I perceive, too, that you don’t see get mentioned much.
Yeah, just go to Germany and have some Ayinger or Spaten or Paulaner or whatever and then come back to the States and buy some dusty bottles of the same off the shelf. That will make anyone understand the caramel/sweet aspect of oxidation.
Good stuff - I think I know exactly what you guys are talking about.
In lighter German beers in the states, I often pick up a honey flavor, which is oxidation. The compound is 2,3-pentanedione, and some discriptions say it has a caramel taste.
Right. I notice a shrinkage of flavor level or less intense (brightness or freshness) flavors. Boxy or cardboard and sherry are classic descriptors which to me are most accurate. I’ve also experienced some slightly metallic flavors in older beers.
I think Gordon hit the high notes of this condition. The best way to recognize this is to do a blind tasting of like examples a few years apart, of course easier said than done.
I’m extremely lucky in that our local bottle shop has all of those in excellent condition.