Beer Forum

All,
I made a ten gallon batch of Janet's Brown Ale that has turned into the most offensive representation of Acetaldehyde that I have ever tasted and smelled. I've gone through and reviewed the causes, and all I can think is that I pulled it off the yeast too soon. I believe that this is the case because the gravity was a little high when I kegged (even though it sat for three weeks). I used three packs of safale 05 added O2 for two minutes. I did not rehydrate it (I know...lazy bastard...).
So my question is this: Can I make a small starter and pitch it into the kegs with the hope that actively fermenting yeast would eat up the excessive acetaldehyde? Or is this a dumper?
Well...if anything I can bottle up a few and save them for BJCP classes.
Thanks in advance.

Hey crupp, thanks for the beers, I have enjoyed them! The Janets does have an intense green apple, which is a shame because the beer underneath is tasty! JZ has mentioned repitching a healthy active starter to clean that up. Perhaps a lager strain if your kegs are cold. Another thought, were there temp swings in your fermentation to knock the yeast out prematurely?

Here's one to try on no more than a glassfull of the beer. If it works you can consider treating the rest. Crush a Campden tablet to fine powder and add a bit to the beer. The theory is that the bisulfite will reduce the acetaldehyde to ethanol (HSO3- + (OH)- + (CH3)CHO ---> (CH3)(CH2)OH + SO4--). This does work in the lab rendering nasty smelling water with a couple of drops of acetaldehyde in it to a neutral smelling solution which doesn't taste of acetaldehyde (but does taste of metabyte) so the question is as to whether the reaction goes as well at beer pH (note than OH- is required) and if it does whether you can get the acetaldehyde note down sufficiently without having objectionable bisulfite levels.

If the level is so high that it is really nasty (to the point where it smells and tasted aldehydic as opposed to apple like - I judged one of these 2 weekends ago and it was so strong I didn't recognize it as acetaldehyde until another judge mentioned it) then the problem is probably a bacterial infection and I wonder if even healthy yeast will be able to reduce it but putting in some kreusen beer is probably worth a try.

Thanks for the advice. I tried the ground Campden tablet. The acetaldehyde went away in the aroma, but it still wasn't pleasant to smell. I made up a starter of 001, and pitched it into the kegs. It started to bubble after a few hours. Who knows...maybe it's working. Either way, I've got nothing to lose, right?

Just a thought but is it possible that you pitched too much yeast? I thought I read that overpitching can starve the yeast and leave acetaldehyde in the beer.

I know it was 10 gallons but 33gm sounds like a lot.

Mr. Malty suggested 27 grams, so I figured what the hell. I guess I hadn't heard that overpitching could produce acetaldehyde?

crupp wrote:Mr. Malty suggested 27 grams, so I figured what the hell. I guess I hadn't heard that overpitching could produce acetaldehyde?

Well, I use Mr. Malty religiously so maybe I'm wrong.