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Johannes 04-19-2006 12:26 PM

Acetaldehyde
 
I have been having some problems with acetaldehyde in my all grain ales. It seems to only affect my higher gravity brews. Could it be that I am racking off the primary too soon and not leaving enough time with maximum yeast contact? I usuallly rack after three days of primary and then let secondary for two to four weeks. Fermentation temps are in the low to mid 60's. It is somewhat drinkable as I have a friend who actually enjoys it, but I don't. Any advice would be appreciated.

Johann

Desert_Sky 04-19-2006 01:36 PM

You rack to secondary after 3 days? Do you notice any signs of fermentation in the secondary? Im just curious because mine are still in an active fermentation state, especially at the 3 day mark.

Heres a little something I found

Quote:

The last steps of alcoholic fermentation in bacteria, plants and yeast involve the conversion of pyruvate into acetaldehyde by the enzyme pyruvate decarboxylase, followed by the conversion of acetaldehyde into ethanol. The latter reaction is again catalyzed by alcohol dehydrogenase, now operating in the opposite direction

Kaiser 04-19-2006 02:02 PM

Quote:

Originally Posted by JimmyBeam
You rack to secondary after 3 days? Do you notice any signs of fermentation in the secondary? Im just curious because mine are still in an active fermentation state, especially at the 3 day mark.

Especially if it is a higher gravity beer :D .

Kai

Johannes 04-19-2006 03:57 PM

I notice little or no activity in the secondary and when I say higher gravity I mean 1056 range, so not to high. I read that it the acet may be due to not giving the yeast enough time to convert the acetal to ethanol. Thanks for the input.

Johann

Monster Mash 04-19-2006 10:02 PM

You should keep it primary for at least a week even if it looks like it is finished. Take a gravity reading before racking to secondary.

Johannes 04-20-2006 12:07 PM

I racked early because of my fear of off flavors from the trub and settled yeast cake. Autolysis and all that junk. I am going to stop worrying about this as it has never happened to me before. Thanks

Johann

RichBrewer 04-20-2006 02:16 PM

Quote:

Originally Posted by JimmyBeam
You rack to secondary after 3 days? Do you notice any signs of fermentation in the secondary? Im just curious because mine are still in an active fermentation state, especially at the 3 day mark.

Heres a little something I found

Quote:

The last steps of alcoholic fermentation in bacteria, plants and yeast involve the conversion of pyruvate into acetaldehyde by the enzyme pyruvate decarboxylase, followed by the conversion of acetaldehyde into ethanol. The latter reaction is again catalyzed by alcohol dehydrogenase, now operating in the opposite direction
This goes right over my head. If I ever have to understand it I'm in big trouble.:cross:

alemonger 04-23-2006 12:05 AM

Let it FINISH fermenting in primary. You don't have to worry about autolysis, etc for several weeks. Move it to secondary (if at all) after 10-14 days in primary, to allow it to clarify a bit more before bottling.

david_42 04-23-2006 02:17 PM

Autolysis isn't a problem unless you leave the brew on the trub for several weeks.

Johannes 04-24-2006 11:00 AM

Good to know David. Stuff I read in other posts had me worried especially since I don't whirlpool or filter my trub from the brew kettle after cooling. Thanks

Johann

Secondary: Young's bitter
Primary: Newcastle Brown
Lagering 1 month: Hatuey
Lagering 2 months: Dos Equis


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