[Jimmy K]

Proper areation leads to yeast health which leads to better, faster attenuation, less lag time, and healthier repitch.

FTW

If you pitch bad yeast all the aeration in the world won't save you me thinks.

[Steve L]

I guess what prompted this post was an off flavor I get rather often. It's kind of a sherry or vinous flavor... not too strong but tends to show up within a few weeks of aging. Interestingly enough, 2 things come up when I do a search... under pitching and under aerating. Currently I aerate with pure O2 at about 45 seconds @ 1 lpm for a 2.5 gallon batch. I try to pitch right on but it is a game of best guess. Which do you think is more likely to be an issue?

[majorvices]

Proper areation leads to yeast health which leads to better, faster attenuation, less lag time, and healthier repitch.

FTW

If you pitch bad yeast all the aeration in the world won't save you me thinks.

But of course!

[Jimmy K]

Well sherry I've always associated with oxidation after fermentation, but more of a long term aging oxidation. I'm not sure what would cause it to show up quickly.  Your aeration procedure sounds fine though. I doubt that is the cause.

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[dmtaylor]

I wonder if you are over-oxygenating.  I don't use pure O2 so I really don't know.  However I do believe there is such a thing.

[Stevie]

My vote is hot side aeration or autolysis.

[klickitat jim]

Keg or bottle? Describe how you transfer.

[majorvices]

I guess what prompted this post was an off flavor I get rather often. It's kind of a sherry or vinous flavor... not too strong but tends to show up within a few weeks of aging. Interestingly enough, 2 things come up when I do a search... under pitching and under aerating. Currently I aerate with pure O2 at about 45 seconds @ 1 lpm for a 2.5 gallon batch. I try to pitch right on but it is a game of best guess. Which do you think is more likely to be an issue?

Sounds like oxidation to me. Are you using a secondary? As Jim asked, kegging or bottling?

Theoretically it is possible to over aerate but unless you are using pure o2 on very cold wort with very fine bubbles for extended periods it seems rather unlikely. And I'm not sure that you would be getting oxidative like off flavors.

[Steve L]

Let's see... My post boil process is putting my kettle in an ice water bath as well as using my immersion chiller to chill down to about 65 usually within 15 minutes (easier to chill when you only do 2.5 gallon batches ) Once it's chilled I whirlpool and let it sit for 15 minutes then transfer to carboy with an autosiphon. I aerate with pure O2 for 45 seconds @ 1 lpm using a 2 micron stone.

  I almost never use a secondary unless I'm going to lager a LONG time, like more than 2 months. Post fermentation, on bottling day, I transfer from carboy to a 5 gallon bottling bucket using an autosiphon. I do stir a bit when I mix in my priming sugar but I'm talking EXTREMELY gently. Sometimes the beer may sit in the bucket for a half hour or so while I prepare the bottling implements. I bottle using a bottling wand connected to the spigot with a 3 inch piece of tubing and cap each bottle as I go. I do use oxy caps but I soak them in starsan so I may be defeating the Oxy scrubbing ability of the liner. I then carb at 75 degrees for 3 weeks and chill for a week before I try the first bottle. Often times the first week post carbing and chilling I get some harsh green flavors (expected). the second week is usually the best. Then the flavors start to fade a bit as it ages further. I had  southern English brown ale that had an awesome chocolate/coffee flavor 2 weeks after carbing, but within 2 weeks after that it faded quite a bit. That is to say it was still a nice beer but when I get a nice complex beer, it seems short lived. Then after 3-4 weeks I get the vinous flavor undertones. Sometimes the vinous flavor comes on a bit faster. I wish I could have correlated that possibly with the ABV of the beers that were affected but I haven't as yet unfortunately. It feels like I'm walking a flavor tightrope and I'm teetering a bit but not falling off, if that makes sense.

[Stevie]

From what I have been told, oxycaps are activated when soaked in sanitizer. I've done this since forever. You should be fine there. They are single use, so once wet the oxy scrubbing ability is gone.

[klickitat jim]

Let's see... It feels like I'm walking a flavor tightrope and I'm teetering a bit but not falling off, if that makes sense.

I deleted all the stuff in the middle because it seems normal process, but the first two words and the last sentence lead me to believe that you are searching for the off flavor. I highly suggest that you find the nearest national judge and have them taste it for you.