How to pitch yeast to absorb acetaldehyde?

I've heard Jamil say on the Brewing Network that pitching yeast into a green apple beer can fix it by absorbing acetaldehyde but I've never done it and am not clear on a few things.

Do I just pour a tube of White Labs into the keg?

Or do I need to make a starter? If so, how much?

How long do I leave it in there before racking off of that yeast?

I assume I should do this at around my regular fermentation temp of 65-67?

Has anyone had success with this that can advise me? Thanks in advance.

Dan

If you just let your beer age properly(especially in the primary) you won't have apple beer.

Aside from that, yeah, repitching some yeast would probably do the trick... but then you need to wait weeks for it to re-uptake and then settle back out. So in short, just let the beer age in the first place... and on the yeast cake can help.

z987k said:

If you just let your beer age properly(especially in the primary) you won't have apple beer.

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Yes. I know. But it's not a theoretical question. I've got a keg of green apple beer.

z987k said:

Aside from that, yeah, repitching some yeast would probably do the trick... but then you need to wait weeks for it to re-uptake and then settle back out.

Click to expand...

Would you do a starter or just pitch a tube? I'm thinking I'd need a fair amount of yeast to do the job that a whole yeast cake would have done if I'd left it alone for another week. I'm thinking about a 1L starter and then tasting it in a couple of weeks.

JollyToper said:

Yes. I know. But it's not a theoretical question. I've got a keg of green apple beer.



Would you do a starter or just pitch a tube? I'm thinking I'd need a fair amount of yeast to do the job that a whole yeast cake would have done if I'd left it alone for another week. I'm thinking about a 1L starter and then tasting it in a couple of weeks.

Click to expand...

I'd do a cheap dry yeast that flocs well.

Also, you could just call it ephimere (Unibroue)

Digging up an old thread here, but I recently did a lager that was pure green apple. I am not sure why, all of my previous lagers turned out excellent, but it was the first pitch of 2206 (which I have heard other reports of this same problem).

Either way, I barely noticed this when transfering to the keg and thought it was mild and would lager-out. 3 weeks later, I took a sample and definitely decided I couldnt drink a keg of the stuff. So I started doing some research. It turns out that acetylaldehyde is very volatile, and the fact that the keg was already carbed could be a huge benefit, as the escaping CO2 at warmer temps would bring the acetylaldehyde right with it.

I took the keg out of the kegerator, and burped the pressure relief valve every day or so for 5 days now. Additionally, I took some yeast cake, added about 8oz of wort to it, let it start fermenting for about 24h and pitched that.

The combination seems to have completely cleared up the problem after only a few days. It delays the whole process though, as I really need to re-lager the beer now, but at least I will have a (at this point it is promising) very good tasting Munich Helles.

Interestingly enough, this was the first in a series of beers with fresh yeast (still did a 4L stirplate starter though) and since I thought it was a lower OG beer (1.043) that I could get away with not doing a D-Rest at the end of fermentation. I think the combination of this is what did it, and I will definitely be doing a D-Rest from now on when I am at about 80% of my expected attenuation.