How much light is too much?

I am wondering how much light is acceptable to subject my beer to in the primary fermenter.

After I put the wort in the primary, aerated and pitched my yeast, I turned the box that the carboy came in upside down and but a hole for the airstopper to stick out of. Is it ok to take the box off to take a peak every once in awhile? Will this hurt the yeast at all. I try to do it with as little light as possible.

How careful do I need to be when exposing the primary fermenter to light?

Thanks a lot!!!

Just a peak now and then isn't gonna hurt anything, especially if it's not sunlight. The UV waves from the sun (and to a lesser extent florescent bulbs) are what does the skunking. There are other factors keeping this from happening in the fermenter also, like the density and turbidity of the liquid, so you really don't have to worry that much. Just keep it out of direct light as much as you can and you will be fine.

your brew is not like a roll of film. you can open the box and take a look. just keep it out of direct sunlight and UV lights.

Thanks guys, thats what I was thinking! Just an overly anxious/nervous noob here...haha

TipsyDragon said:

your brew is not like a roll of film.

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what's "film" ?

Hang Glider said:

what's "film" ?

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you know. that stuff us old timers used to put in cameras to take pictures. before you young whiper snapers made it all digital.

I still have 2 rolls of K64 Kodachrome in my freezer. had better use it soon. Only 1 place in the US still processes it.

I "accidently" left my clear carboy exposed in my kitchen for over a week. No direct sunlight but still loves of UV rays. I did not notice any funky flavors.

rcreveli said:

I still have 2 rolls of K64 Kodachrome in my freezer. had better use it soon. Only 1 place in the US still processes it.

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Wow, I just looked up some old Kodachrome photos and the color depth and quality is amazing. They don't make 'em like they used to... or whatever you old fellas say.

Now to say something on topic, I wrap a shirt around mine and set it in a closet. Light definitely gets in, never had any problems with skunking.

IceFisherChris said:

I "accidently" left my clear carboy exposed in my kitchen for over a week. No direct sunlight but still loves of UV rays. I did not notice any funky flavors.

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everything i've read says its direct UV exposure that kills a brew. apparently indirect exposure is ok.

I have used a flashlight to monitor the end of the racking cane during racking, with no real issues. I typically ferment in my upstairs bathroom, which is dark 99.99% of the time, except when I take my daily #2, then I just leave the shower curtain shut. never had an issue.

Rook said:

I have used a flashlight to monitor the end of the racking cane during racking, with no real issues. I typically ferment in my upstairs bathroom, which is dark 99.99% of the time, except when I take my daily #2, then I just leave the shower curtain shut. never had an issue.

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talk about overkill.

seriously.... I brew outside, granted I don't ferment outside, I keep my windows open during transfers and whatnot...

elmetal said:

seriously.... I brew outside, granted I don't ferment outside, I keep my windows open during transfers and whatnot...

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The skunking reaction doesn't happen until fermentation has occurred so brewing outside isn't an issue, but after it can happen extremely quickly. As part of a brewing class I took we purposely skunked a pint of beer to see how quickly we noticed a difference and I could tell a difference in about 3 minutes of direct sun, and after about 15 is was pretty bad.

Of course like I said earlier, a beer in the fermenter isn't going to have the same issues, but it can happen, even with indirect exposure.

BarleyWater said:

The skunking reaction doesn't happen until fermentation has occurred so brewing outside isn't an issue, but after it can happen extremely quickly.

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I realize that, which is why I said "granted I don't ferment outside".

on the other hand, I thought skunking happened because of alpha acids' reaction with UV light, which means fermentation has nothing to do with it.

Am I right?

I don't cover mine at all and I don't notice any skunking. Never had a judge comment about skunking either.

I also don't keep it in bright sunlight. Sometimes it's in the bathroom. It gets some indirect sunlight in there and some light from the fluorescents.

I think indirect exposure is fine. However do not pour yourself a pint of IPA and proceed to sip it on the sun drenched veranda.

elmetal said:

I realize that, which is why I said "granted I don't ferment outside".

on the other hand, I thought skunking happened because of alpha acids' reaction with UV light, which means fermentation has nothing to do with it.

Am I right?

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The yeast provides Vitamin B2 which acts as a photosynthesizer, catalyzing the conversion of oxygen to singlet oxygen. This oxygen then “destroys” isohumulone and in the process radicals are formed. The radical reacts with sulfur containing proteins, forming a thiol called 3-methylbut-2-ene-1-thiol, which is the same chemical found in skunks. Without the yeast present, the reaction can't begin to take place.

BarleyWater said:

The yeast provides Vitamin B2 which acts as a photosynthesizer, catalyzing the conversion of oxygen to singlet oxygen. This oxygen then “destroys” isohumulone and in the process radicals are formed. The radical reacts with sulfur containing proteins, forming a thiol called 3-methylbut-2-ene-1-thiol, which is the same chemical found in skunks. Without the yeast present, the reaction can't begin to take place.

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This should be in the brewing science forum . I wish I could take a brewing class.

so using 50 uv led's as a nightlight for the fermenter is a BAD idea?