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Acetaldehyde

What is the major cause of Acetaldehyde flavor in beer? Just got some scoresheets back and this was a recurring remark in my IPA. How do I get rid of it? I usually ferment at the low end of teh yeast range but may not have always pitched enough yeast.

Acetaldehyde is a chemical in the pathway to making alcohol. Too much generally indicates that the beer isn’t done fermenting yet or poor yeast health from underpitching and other causes.

+1 Racking out of primary and off the yeast cake too soon is a prime cause of acetaldehyde. When you ferment at the low end of the temp range, things go slower. Therefore you need to leave the beer on the yeast longer to let it clean up. It also helps to warm it up towards the end of fermentation, at that point you don’t get more esters and the higher temp helps the yeast continue to metabolize the secondary products like diacetyl and acetaldehyde.

You can rack to secondary if you’re worried about oxidation, just rack over a good slug of the yeast cake so things don’t stall out.

If you’re unable to control your ferment temps accurately, be sure your ambient temp is stable and not dropping by 10F at night. You’ll also need to keep the beer in the fermenter for an extra week or two.

Be sure you’re pitching enough yeast : http://www.mrmalty.com/calc/calc.html

Ok so I am sure that I am leaving my wort in the primary long enough, (always 3 weeks) my temps stay pretty steady, 58-62 using 1056, so I am assuming that I am not pitching enough yeast? I have just started using Beersmith and on the page/tab that shows how much to pitch it seems that I am a little short.

Is a 1.5 liter starter standard for a “regular” beer, say 1.056-1.070? I have only been making starters with about .5-1 liter with 1 cup DME.

Thanks
Mike B

The best thing is to review the info at mrmalty.com on yeast starters and how much to pitch.
The temperature has a lot to do with it also. At 60F you’ll need to pitch about 1/3 more than at room temp.

A cup of DME in a starter wort would be fine for 1L (1.040) but too high for 0.5L (1.080). You don’t want to stress the yeast right out of the gate.

Also I’d maybe ferment a little warmer (62-66F), at 58F even 3 weeks might not be long enough. Obviously theres something going on if you actually have an acetaldehyde problem. Can you taste it?

[quote=“tom sawyer”]A cup of DME in a starter wort would be fine for 1L (1.040) but too high for 0.5L (1.080). You don’t want to stress the yeast right out of the gate.

Also I’d maybe ferment a little warmer (62-66F), at 58F even 3 weeks might not be long enough. Obviously theres something going on if you actually have an acetaldehyde problem. Can you taste it?[/quote]

I can’t taste it (don’t know what it would taste like?) but it was noted on both of my scoresheets from the bluebonnet brewoff by both judges. It scored a 23 with one judge stating “Acetaldehyde is a major fault.”

I actually thought it was one of the best tasting beers that I had made in a while :oops:

So a little bigger starter and a little longer time at that temp or up the temp a bit?

Tastes/smells like green apple.

Bigger starter, up the temp a little.

How long had it been in the bottle when it was judged? I had a pale ale after a week in the bottle once…you know, because I was impatient/excited. Green apples. Totally. In 3 weeks, it was great.

You didn’t use Calypso hops, did you?

[quote=“tom sawyer”]Tastes/smells like green apple.

Bigger starter, up the temp a little.[/quote]

Yeah I was not getting any green apple smell, it did have a little fruity taste to it but I would not describe it as green apple. I think they made the comment esters as well.

[quote=“jezmez68”]How long had it been in the bottle when it was judged? I had a pale ale after a week in the bottle once…you know, because I was impatient/excited. Green apples. Totally. In 3 weeks, it was great.

You didn’t use Calypso hops, did you?[/quote]

No calypso hops, centennial and cascade and it had been bottled from my keg. Kegged for about 6 weeks probably 3-4 weeks in the bottle by the time of judging.

Your process seems good for the first two weeks of fermentation. Keep the temp low, especially for American styles, to keep the beer clean. With my swamp cooler setup I generally ferment right around 60 for ten days or so, then let it free rise in the swamp cooler (I don’t replace the frozen water bottles) for a few days. Then it’s pulled from the cooler altogether and sits at room temp for a diacytel rest for a few days. The warmer temps won’t throw esters/alcohol at that point, and I find the D-Rest also knocks out acetaldehyde, which I did experience in a few American pales early in my brewing days.

I’ll usually then cold crash before racking to a cool secondary, or directly to a keg, to drop yeast etc out, but only after the yeast has had enough time to clean up.

Cheers.

When I plan to make a high gravity beer, I usually plan on making a low-gravity beer first with the yeast that I want to use for the strong beer, basically using the first beer as a “starter” for the strong beer. I did a scottish 60 and then a wee heavy and an american pale and then an american barleywine this way last fall, and it worked great, just pitched about 3/4 of the yeast cake into the stronger beer, and you save a little money on yeast as well.

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