Author Topic: isovaleric acid - sweaty socks  (Read 1106 times)

Offline goschman

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isovaleric acid - sweaty socks
« on: July 26, 2016, 09:05:03 PM »
I am trying to identify an off flavor in a pale lager that was brewed with W34/70. It is not very strong and seems to be dissipating. It seems to be something I am very sensitive to. I get a sweaty sock type aroma and taste in the beer however like I mentioned, it is more of a background note. I see stale cheese as a common descriptor however that isn't necessarily what I detect. This beer is in a competition this weekend and I just want to be prepared for the critiques.

My buddy says he doesn't notice it and I have detected it certain pale lagers before at brewpubs where my friends didn't taste or smell it. Is this likely isovaleric acid? Will it continue to dissipate with continued lagering? The two main causes I see are old hops and brett infection which doesn't seem to apply in this circumstance.
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Offline jeffy

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Re: isovaleric acid - sweaty socks
« Reply #1 on: July 26, 2016, 09:11:12 PM »
Sometimes 34/70 throws off a little sulfur, which is more likely to dissipate after a few minutes than isovolaric.  Are you especially sensitive to sulfur compounds?
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Offline goschman

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Re: isovaleric acid - sweaty socks
« Reply #2 on: July 26, 2016, 09:13:57 PM »
Sometimes 34/70 throws off a little sulfur, which is more likely to dissipate after a few minutes than isovolaric.  Are you especially sensitive to sulfur compounds?

I don't believe so. I have less than 10 lagers under my belt and have used 34/70 for all of them. I have brewed this particular beer 3 times and have never detected this character. This character has seemed to dissipate after days in the keg but not within minutes in the glass.
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Offline dmtaylor

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Re: isovaleric acid - sweaty socks
« Reply #3 on: July 26, 2016, 09:16:58 PM »
I got isovaleric in a recent batch.  I've decided I should replace my transfer hoses and racking cane.  It's been a few years, so a contaminant from rubber & plastic components might possibly be the culprit.  Otherwise I have a really hard time figuring out how else it might have happened.

EDIT: It actually could be old hops.  That might be an even more likely culprit.  But, I'm going to replace the old rubber & plastic regardless because it's time.
« Last Edit: July 26, 2016, 09:20:59 PM by dmtaylor »
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Offline goschman

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Re: isovaleric acid - sweaty socks
« Reply #4 on: July 26, 2016, 11:30:02 PM »
Just sampled again and the off flavor seems to has dissipated even further. It is tasting more like a Czech pils than an international pale lager which I entered it as. Hopefully not another misentered beer. I assume they will be combining most of the light lager categories.

I am still curious about what is was.
« Last Edit: July 26, 2016, 11:52:28 PM by goschman »
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Offline santoch

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Re: isovaleric acid - sweaty socks
« Reply #5 on: July 27, 2016, 12:51:16 AM »
Isovaleric acid is definitely hop related.

The funny thing about it is that major parts of the population can't even detect it at any level.  I went to the Siebel Sensory Perception class at GABF back in 2009 (God, has it been that long?) and while half the class sipped away at the sample straining to find something wrong, the other half of the class was making gagging noises and looked like they were going to hurl.
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Offline goschman

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Re: isovaleric acid - sweaty socks
« Reply #6 on: July 27, 2016, 01:55:23 AM »
Isovaleric acid is definitely hop related.

The funny thing about it is that major parts of the population can't even detect it at any level.  I went to the Siebel Sensory Perception class at GABF back in 2009 (God, has it been that long?) and while half the class sipped away at the sample straining to find something wrong, the other half of the class was making gagging noises and looked like they were going to hurl.

Good to know. I read somewhere today that it was usuall hop related but could also have to do with stressed yeast so I thought that might be a culprit. Whatever it is seems to be a byproduct of fermentation which is fading with extended lagering time.
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Offline mabrungard

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Re: isovaleric acid - sweaty socks
« Reply #7 on: July 27, 2016, 01:18:12 PM »
I got isovaleric in a recent batch.  I've decided I should replace my transfer hoses and racking cane.  It's been a few years, so a contaminant from rubber & plastic components might possibly be the culprit.  Otherwise I have a really hard time figuring out how else it might have happened.

Dave, do you use iodophor or bleach occassionally for sanitizing? After Mark's illustration that Starsan doesn't work on all spoilers, I've been more open to iodophor use. I'm still leary of using bleach on my plastics and hoses, but it sure is an effective sanitizer. Occassional Hose replacement is probably still a good policy.
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Offline dmtaylor

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Re: isovaleric acid - sweaty socks
« Reply #8 on: July 27, 2016, 01:30:27 PM »
Dave, do you use iodophor or bleach occassionally for sanitizing? After Mark's illustration that Starsan doesn't work on all spoilers, I've been more open to iodophor use. I'm still leary of using bleach on my plastics and hoses, but it sure is an effective sanitizer. Occassional Hose replacement is probably still a good policy.

I haven't used bleach for many many years.  I agree, it would probably be a good idea to switch sanitizers more often.  This advice applies to all homebrewers of course, not just me or people who are having problems.  Maybe every 5 or 6 batches or so we should be switching it up.  And the hose thing, definitely more often than I've been doing (I think it's been about 5 years now).
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Offline beersk

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Re: isovaleric acid - sweaty socks
« Reply #9 on: July 27, 2016, 03:40:07 PM »
Isovaleric acid is definitely hop related.

The funny thing about it is that major parts of the population can't even detect it at any level.  I went to the Siebel Sensory Perception class at GABF back in 2009 (God, has it been that long?) and while half the class sipped away at the sample straining to find something wrong, the other half of the class was making gagging noises and looked like they were going to hurl.

Would agree it's probably hop related. Every beer I made with the last pound of Cascade I had had a dirty sock aroma suggesting isovaleric acid because of old hops. They were crazy old, but it was only in those beers made with those hops.
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Offline blair.streit

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Re: isovaleric acid - sweaty socks
« Reply #10 on: July 27, 2016, 03:59:32 PM »
Dave, do you use iodophor or bleach occassionally for sanitizing? After Mark's illustration that Starsan doesn't work on all spoilers, I've been more open to iodophor use. I'm still leary of using bleach on my plastics and hoses, but it sure is an effective sanitizer. Occassional Hose replacement is probably still a good policy.

I haven't used bleach for many many years.  I agree, it would probably be a good idea to switch sanitizers more often.  This advice applies to all homebrewers of course, not just me or people who are having problems.  Maybe every 5 or 6 batches or so we should be switching it up.  And the hose thing, definitely more often than I've been doing (I think it's been about 5 years now).
I've been considering building a "hose sanitizer" using my sump pump to recirculate iodophor through various diameters of tubing I use for transfers. Ideally, I'd like to find a "stepped barb" so I could just slip the tubing over the end and let it recirc for a few minutes, then switch ends since the end on the barb probably wouldn't get much action.

My goal is not to avoid replacing tubing but to get a few more uses out of it. Right now with all the various tubing I use for racking, keg to keg transfers, etc, I find that I'm constantly throwing away tubing that I've used once or twice because I can't remember the vintage or it just doesn't "look right". I'm probably overly paranoid about this, but given that tubing is difficult to clean, sanitize and dry thoroughly, it seems way too easy to get mold or wild yeast going in there (which are less likely to be killed by StarSan).

Offline brewinhard

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Re: isovaleric acid - sweaty socks
« Reply #11 on: July 27, 2016, 05:41:46 PM »
For the past few years I have been diligent about replacing my plastic equipment (siphon tubing, auto-siphon, and wine thief) once every year. I feel that 30 bucks per year is a good insurance to have peace of mind that I am doing my very best to minimize infections.

Offline HoosierBrew

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Re: isovaleric acid - sweaty socks
« Reply #12 on: July 27, 2016, 05:44:57 PM »
+1. I replace my plastic things every year as well. Haven't had an infection in several years.
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Offline brewinhard

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Re: isovaleric acid - sweaty socks
« Reply #13 on: July 27, 2016, 05:47:41 PM »
Isovaleric acid is definitely hop related.

The funny thing about it is that major parts of the population can't even detect it at any level.  I went to the Siebel Sensory Perception class at GABF back in 2009 (God, has it been that long?) and while half the class sipped away at the sample straining to find something wrong, the other half of the class was making gagging noises and looked like they were going to hurl.

Would agree it's probably hop related. Every beer I made with the last pound of Cascade I had had a dirty sock aroma suggesting isovaleric acid because of old hops. They were crazy old, but it was only in those beers made with those hops.

Were those hops kept cold and sealed?

Offline Stevie

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Re: isovaleric acid - sweaty socks
« Reply #14 on: July 27, 2016, 05:50:49 PM »
Interesting. My wine their is at least 7 years old. It's the three piece style and I only rinse it with hot water between uses. I do clean it on brew days when I have a bucket of cleaner.

Tubing is every year or two I guess.