Oxidation?

Due to various things that tend to come up in life, and a good dose of laziness besides, I just kegged (and bottled a bit of) an Irish Red ale that I put into the fermenter about 9 months ago.

I was prepared for it to be horrible and to just give up on it, but I decided it wasn't going to cost me anything but an hour to keg/bottle it and see what happened.

I bottled 12 bottles and kegged the rest of it. (Also my first attempt at kegging, which went fine.)

I tasted the hydrometer sample (1.011 FG) before I kegged it, and it tasted okay. So I was thinking at that point that maybe it'd be okay after all.

I chilled the keg to about 40F and force carbed it.

After it was carbonated, it had a background flavor of old stale bread, which from what I've read is a sign of oxidation.

Given that it was not oxygenated while it was hot, or after fermentation was done, and that it was fermented in a glass carboy (no oxygen coming through any plastic), where did the oxidation come from? The airlock on the carboy had liquid in it for the whole time it was in the fermenter (I topped it up a few times).

I didn't use a secondary for this beer, so it was on the yeast the whole time.

I was fully expecting autolysis and an accompanying rotten meat taste (which thankfully it does not have), but the stale bread flavor, I'm not sure where it picked up.

Is stale bread also a flavor that can come from sitting on the yeast (way) too long?

Not sure what is causing it but here is an excellent link to the show "Brew Strong". Look for the show labeled "hot side aeration". Apparently hsa is a myth. Also a lot of talk about oxidation.

The Brewing Network.com - Shows and Podcasts: Brew Strong

Did you purge the keg with CO2 before filling it with beer? Did you purge all gas from it again after filling? If not when you force carbed it you also force "aired" it.

I didn't purge the keg before I filled it, but I was careful to put the end of the siphon hose all the way to the bottom of the keg so as not to aerate the beer.

I did purge the air from the keg after it was filled.

Today I tried the beer again and it was a little better than yesterday, maybe just because it's a little more carbed.

Ok, so it's probably not oxidized from that. Cleanliness/Sanitation? Was it in light for any extended period?

I thought about it some more last night, and I now think you are right that this was the result of the air that was in the keg when I siphoned the beer into it.

I forgot one important detail yesterday when I first read your reply:
Even though I was careful siphoning it into the keg, I did carry it out to the car and drive it about four blocks to a friend's place and purged the air and force carbed it there. I was careful about it, and I didn't notice it sloshing about, but there was certainly the opportunity for it to pick up some air there.

I would blame sitting on the yeast for 9 months. That can cause bready flavors I've read.

conpewter said:

I would blame sitting on the yeast for 9 months. That can cause bready flavors I've read.

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+1 on this. There is normal yeast autolysis which can give rise to bready/yeastie flavors. As long as the beer isn't too warm, or infected, this can often can be subtle. Then there is the nasty autolysis which can arise is mistreated beers - too warm, infected, O2 exposure etc.

Sounds reasonable. I had never heard of bready flavors from autolysis.

Yeah I think it's just autolysis. It's possible, after it sits for a bit, it may get better. I had some autolyzed yeast in a batch of Apfelwein that sat for 4.5 months without being racked, after a few months in the keg the soapy cracker flavor was gone once all the dead yeast settled out to the bottom.

I just did the same thing, extra long age in the fermenter, except that I was racking to the keg from a secondary, so I had not left it on the yeast. I had not issues with any bread flavors which I attribute to the secondary. I force carbed as well, and the first pulls taseted a little off, but improved to a very drinkable ale once the carb levels had stabilized after a couple of days.

Wiki article on autolysis in wine, which is something they actually want (think champagne)
http://en.wikipedia.org/wiki/Autolysis_(wine)

The effects of autolysis on wine contributes to a creamy mouthfeel that may make a wine seem to have a fuller body. The release of enzymes inhibits oxidation which improves some of the aging potential of the wine. The mannoproteins improve the overall stability of the proteins in the wine by reducing the amount of tartrates that are precipitated out. They may also bind with the tannins in the wine to reduce the perception of bitterness or astringency in the wine. The increase production of amino acids leads to the develop of several flavors associated with premium Champagne including aromas of biscuits[5] or bread dough, nuttiness[6] and acacia. As the wine ages further, more complex notes may develop from the effects of autolysis.[1]

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It's been a couple of weeks in the keg now, and the stale bread flavor has completely disappeared.

Now I wonder, since this is the first brew I've kegged, if there was just some yeast sediment at the bottom of the keg that I was tasting in the first several pulls (although they looked perfectly clear to me).