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Old 12-17-2012, 12:30 AM   #1
twbalding
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Dec 2012
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Just as the post states, I'm curious about how light affects my beer as it ferments in a clear glass car boy. Can anyone explain why we cover or put our fermenters in a dark place?



 
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Old 12-17-2012, 12:40 AM   #2
Fletcher21
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Apr 2011
Oregon City, Oregon
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It's chemistry... Long periods of light effect yeast and create a flavor known as skunking ( not preferred by most) so we cover or leave in the dark and also keep beer in dark bottles.



 
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Old 12-17-2012, 12:43 AM   #3
prpromin
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Grand Rapids, MI
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This is from the last day or so - it's about brown bottles, but read on - it applies here, too:
http://www.homebrewtalk.com/f14/beer...ottles-374405/

 
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Old 12-19-2012, 03:34 AM   #4
fergyrock
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Dec 2012
Reno, Nevada
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A question pertaining to this topic.

With my first batch it had been in Firm bucket for 7 days and now a carboy for around 7 days. Stays in a mostly shut closet, but the wife and kid leave it open regularly. I would say it has around 1-2 hours a day on average of exposure to a small (13w) compact florescent light around 10ft away.

Would anyone assume this would skunk an average to heavily hopped ale? there is no detectable hint of a skunk aroma to the beer right now and it smell's good.

I just started covering it after discovering that floro's may skunk it. BUT... I was wondering if the odor will manifest later on? or if it will effect my other batch in white opaque firm buckets?

I will always play it safe and cover from now on, another good lesson learned.

 
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Old 12-19-2012, 04:36 AM   #5
scoundrel
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Quote:
Originally Posted by Fletcher21 View Post
It's chemistry... Long periods of light effect yeast and create a flavor known as skunking ( not preferred by most) so we cover or leave in the dark and also keep beer in dark bottles.
It actually the hops that skunk, not the yeast.
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Old 12-19-2012, 04:44 AM   #6
scoundrel
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Quote:
Originally Posted by fergyrock View Post
A question pertaining to this topic.

With my first batch it had been in Firm bucket for 7 days and now a carboy for around 7 days. Stays in a mostly shut closet, but the wife and kid leave it open regularly. I would say it has around 1-2 hours a day on average of exposure to a small (13w) compact florescent light around 10ft away.

Would anyone assume this would skunk an average to heavily hopped ale? there is no detectable hint of a skunk aroma to the beer right now and it smell's good.

I just started covering it after discovering that floro's may skunk it. BUT... I was wondering if the odor will manifest later on? or if it will effect my other batch in white opaque firm buckets?

I will always play it safe and cover from now on, another good lesson learned.
It should be fine. 7 days of constant light... maybe. Just wrap your carboys in a towel going forward. Long trips over seas and many a nights in a florescent cooler wreaks havoc on green and clear bottles. Not to mention sunlight. It's by far the worst. I just don't see why breweries still use them. It's just stupid.
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Old 12-19-2012, 04:45 AM   #7
Calder
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If you can't taste or smell skunk, you are OK. Someone with more sensitive taste or smell might detect it if it is there, but probability is you are OK.

There is no part way. You notice it or not.

A 13 watt CFL 10 feet away is probably not going to affect it much.

Like most people, just use your wife's favorite T-shirts to cover your fermenters and the beer will be OK. ....... You might have a problem, but the beer will be fine!

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Old 12-19-2012, 04:49 AM   #8
bobbrewedit
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Sep 2012
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I've never experimented with this intentionally, but I wonder exactly how sensitive a beer is to light. Newcastle Brown comes from England in clear glass and I don't find it skunky, certainly not when compared to heineken.

 
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Old 12-19-2012, 04:59 AM   #9
MustBeZ
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From what I understand Newcastle doesn't skunk because they use hop extracts rather than pellet or cone hops. Isomerized alpha acids are the how a beer skunks, and I'm not sure the scientific reason behind those extracts not skunking in the light but they figured out a way.

 
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Old 12-19-2012, 05:02 AM   #10
fergyrock
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Thanks to both of you, I assumed if I couldn't smell it, it would be good to go. and now that its covered I guess I was just worried about the skunk developing after the fact.

Got a T shirt on the Ferment bucket now and actually got a good idea for the carboy when I walked into the garage tonight. I had recently used some of that foil-lined-bubblewrap type insulation on the garage door and had enough left to make a pretty slick cover for the carboy. No light can get through and will keep the temp more constant with day/night temp changes in the house. Thought about it for the bucket too but then realized it would probably raise the temp too much by holding in the fermentation heat, maybe be OK after it has slowed down though.



 
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