Brewed a beer a little while ago that fermented like crazy (pitching to FG in about 3 days or so). Got wrapped in stuff IRL, and had to leave the brew inside the primary for longer than normal… Somewhere like 4-5 weeks total. Since it fermented so quickly (to over 10% abv nonetheless), I had decided to let it sit for a bit longer anyways, to make sure it aged better and didn’t get too much boozey heat.
Well I transferred to a secondary a few nights ago, just so it wasn’t sitting on the trub any more. When I popped the fermenter top, it had a really distinct acetaldehyde smell (resembled a cidery smell). I took a sample for tasting, and I don’t taste anything crazy, it actually has sort of a bland taste to me but oh well.
I know acetaldehyde is necessary to create the ethanol, and I know in the past I have merely had to wait it out and eventually the smell disappeared. My question is… Has anyone ever had a brew where an acetaldehyde smell did not disappear? Besides being “green”, I don’t know of a reason why such an off-flavor would develop, and I’m pretty confident in my cleaning methods. Any insights or feedback?
Well there was probably alot of gas that was “trapped” in your fermenter that you got a good wiff of. Since you couldn’t taste anything it is probably fine. After you keg it if the oder persists vent the keg a few times.
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I know that smell well. I associate it as a yeasty smell. If you don’t taste green apple then there is nothing to worry about.
Alright thanks guys. This just happened to be the longest I left the beer on top of trub, and the first time I reached over 10% abv… Nevermind the first time my fermentation completed so quickly… So I wasnt sure.
Let’s say, hypothetically, that the beer DID have that acetaldehyde taste… What should I do? Like I said, I’ve merely waited it out and all has worked out in my past. I have also read about people pitching more yeast to complete the fermentation, as well as krausening. Curious how others attack this problem when it arises.
Acetaldehyde is usually an indication of an unfinished or incomplete fermentation. I have only ever encountered it on my very first beer, many years ago. But I can remember the taste distinctly as a green apple flavor. There’s no escaping it when you have it. You won’t be saying to yourself, “I think I can taste it.” That said acetaldehyde production is a natural part of the process and some yeasts (typically lager yeasts) leave a little behind I’ve heard.
The typical advise is to age out acetaldehyde by letting your healthy yeast population finish its job. Because you extended your normal fermentation time, and you know what you are doing, we have to assume that this is not an issue. If you had a usually large amount of headspace in your fermenter one might have concerns of other aerobic producers of acetic acid.
Not a lot of headspace, certainly no more than normal. I made 5.5 gallons and used a fermenting bucket as per usual.
The yeast was 2 packets of Trappist ale dry yeast due to a beer over 10% abv. I don’t know if the fast fermentation had anything to do with it. It’s been about 6 weeks since brew day, but the fermentation was technically finished in about 4.5 days or so. This was my first time hitting double digits in alcohol, first time using 2 dry packets, first time using this particular yeast, and first time the fermentation was so fast. Those are the only real variables that are new from my norm
I already said you’re fine, hypothetically and IRL 
Bottle it and move on to the next brew.
