Author Topic: Acetaldehyde  (Read 1712 times)

Offline klickitat jim

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Acetaldehyde
« on: April 12, 2013, 03:46:34 AM »
Given a recent experience with kegging an ale too soon and learning what that green apple rubber glove came from, how do you know when Acetaldehyde is gone?

My current brews are lagers OG 1.050, that hit 1.020 in a week. I raised the temp from 50 to 60. After a week at 60 they are at 1.010. I want to start my drop to 35 but I'm leery of Acetaldehyde.

Any knowledge on this would be awesome.

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Offline AmandaK

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Re: Acetaldehyde
« Reply #1 on: April 12, 2013, 04:37:39 AM »
I usually taste my hydrometer samples.
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Offline klickitat jim

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Re: Acetaldehyde
« Reply #2 on: April 12, 2013, 04:53:30 AM »
I'll try that.

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Offline bbkf

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Re: Acetaldehyde
« Reply #3 on: April 12, 2013, 05:28:09 AM »
You get used to how yeast strains work.  But until that happens, you have to rely on taste/smell like amanda sugested.

Offline mtnrockhopper

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Re: Acetaldehyde
« Reply #4 on: April 12, 2013, 09:26:08 AM »
I usually taste my hydrometer samples.
This. Acetylaldehyde is something yeast clean up after fermentation. If fermentation is done and you don't taste it, you're good to go.
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Offline kylekohlmorgen

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Re: Acetaldehyde
« Reply #5 on: April 12, 2013, 09:53:37 AM »
How fast are you raising the temp for your diacetyl rest? You may actually create acetaldehyde if you stress the yeast by raising/lowering the temp to quickly.

About 1-2 deg F per day is a safe bet.

Any yeast stress can yield acetalaldehyde - underpitching, under-aerating, temp. fluctuations, etc. Check all that out as well.

I've had this issue with my kolsch and found that I need about 1.5x the amount of yeast recommended by Mr. Malty. O2 and temp. control really helped, too.
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Offline morticaixavier

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Re: Acetaldehyde
« Reply #6 on: April 12, 2013, 01:14:16 PM »
If you find some acetaldehyde you can sometimes mitigate it with an even warmer rest than your diacetyl rest. Acetaldehyde has a boiling temp of around 72f IIRC. so it will gas out if you keep the finished beer there for a couple days.
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Offline dmtaylor

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Re: Acetaldehyde
« Reply #7 on: April 12, 2013, 02:04:19 PM »
If you find some acetaldehyde you can sometimes mitigate it with an even warmer rest than your diacetyl rest. Acetaldehyde has a boiling temp of around 72f IIRC. so it will gas out if you keep the finished beer there for a couple days.

^^^ This ^^^
Dave

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Offline klickitat jim

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Re: Acetaldehyde
« Reply #8 on: April 12, 2013, 04:45:36 PM »
My d rest temp increase was done in one chunk. I didn't know about stepping up to that. Will next time.

I'm going to go take another reading and taste. Maybe I'm there and can start my stepped drop to 35.

Thanks for all the great info.

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Offline klickitat jim

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Re: Acetaldehyde
« Reply #9 on: April 12, 2013, 05:13:31 PM »
The bohemian is 1.008nd tastes clean. The American is 1.010-09 and tastes clean. I've started my crash drop. Will keg them in a week.

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Offline AmandaK

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Re: Acetaldehyde
« Reply #10 on: April 13, 2013, 07:21:01 PM »
If you find some acetaldehyde you can sometimes mitigate it with an even warmer rest than your diacetyl rest. Acetaldehyde has a boiling temp of around 72f IIRC. so it will gas out if you keep the finished beer there for a couple days.

For reals? I think this just blew my mind.

Or maybe it's the wine I'm drinking.  ;D
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Offline james

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Re: Acetaldehyde
« Reply #11 on: April 13, 2013, 10:12:03 PM »
How fast are you raising the temp for your diacetyl rest? You may actually create acetaldehyde if you stress the yeast by raising/lowering the temp to quickly.

About 1-2 deg F per day is a safe bet.

Any yeast stress can yield acetalaldehyde - underpitching, under-aerating, temp. fluctuations, etc. Check all that out as well.

I've had this issue with my kolsch and found that I need about 1.5x the amount of yeast recommended by Mr. Malty. O2 and temp. control really helped, too.

I'd agree with this.  It seems like most of the time I've experienced acetalaldehyde it has been from extreme underpitching 

Offline tschmidlin

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Re: Acetaldehyde
« Reply #12 on: April 14, 2013, 01:57:21 AM »
I've never gotten it from crash cooling though.  For what it's worth.
Tom Schmidlin

Offline kylekohlmorgen

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Re: Acetaldehyde
« Reply #13 on: April 16, 2013, 04:15:52 AM »
I've never gotten it from crash cooling though.  For what it's worth.

I guess I always associated "crash cooling" with post-fermentation and "diacetyl rest" with active fermentation.

Temp swings AFTER fermentation = ok.

Temp swings DURING fermentation not ok.
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Offline tschmidlin

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Re: Acetaldehyde
« Reply #14 on: April 16, 2013, 12:31:08 PM »
Oh, i see what you're saying.  Yeah, I'll agree with that.
Tom Schmidlin