Acetaldehyde off flavors in my beers...

[Javaslinger]

My last two brews have had a powerful Acetaldehyde flaw.

One, a british brown ale, appears to have gotten infected. There was some floating sediment in the bottles and they foamed up considerably upon opening. Interestingly they just smell of acetaldehyde and are not source or putrid. They don't taste much like a brown ale alas.

The other, sadly an expensive Russian Imperial Stout, also is smelling very strongly of acetaldehyde. This one does not seem infected however. It's been aging for about 3 months and the off flavor/smell just seems to be getting stronger. I used a huge starter and oxygenated as well as I could using a wine whip. Temps were maintained in the mid 60's and fermentation was fully completed.

These were not sequential brews and the the in between beer came out just fine...

Any ideas where I might be getting this off flavor from? I've rigorously cleaned by bottling bucket hoses... Crossing my fingers as I'm about to bottle a very expensive NEIPA.

 

[jdauria]

The best ways to avoid acetaldehyde in your homebrewing are to

1. Maintain flawless sanitation practices.
2. Pitch an appropriate amount of yeast.
3. Fully oxygenate wort at pitching.
4. Avoid racking beer off the yeast trub before fermentation is complete.
5. Avoid introducing oxygen into your beer after fermentation.

So you are cleaning everything...sanitizing too I assume? Have you taking the bottling bucket valve apart and cleaned that? How about the valve on your brewing kettle if you have one?

2. Pitching enough yeast...seems you are ok there with a starter.
3. You use a whisk..so that's ok..pure O2 would be better.
4. How long are you leaving the beer on the yeast? Just because a beer may be at final gravity in a week, it's good to leave it for 2-3 weeks before transferring off the trub so the the yeast can clean up after it's self.
5. Introducing oxygen after fermentation...this is probably an issue where you using a bottling bucket and bottle from it as it's hard to keep oxygen out during this process.

Acetaldehyde is something seen in young beers a lot. I would let the RIS just go for another 3 months at least and see if it cleans up. Are you aging it in bottles or in the fermenter? If fermenter, just leave it in and don't even open it for 3 months. The more you open a carboy or bucket, the more oxygen you let in.

 

[MaxStout]

I had a couple infected batches a few years ago. Traced it to plastic parts. Now, when I'm not using the bottling bucket, I remove the spigot, disassemble it and store it in a jar of Starsan until next use. I replace plastic tubing often. That's cheap and I don't want to let it become an infection point again.

 

[Javaslinger]

Acetaldehyde is something seen in young beers a lot. I would let the RIS just go for another 3 months at least and see if it cleans up. Are you aging it in bottles or in the fermenter? If fermenter, just leave it in and don't even open it for 3 months. The more you open a carboy or bucket, the more oxygen you let in.

This makes me feel a little better. It is a big RIS so maybe it just needs more time. I didn't realize that acetaldehyde was something that would dissipate and clean up over time in the bottle. I am aging it in the bottle.

Thanks for the detailed response!