white trashbags ruin beer?

i brewed like i normally do (ive been brewing for quite a while and never had a bad batch) i brewed 4x 10 gallon batches, different yeasts different beers, different hops, and the only thing i changed about my process is i used thin white garbage bags to cover the carboys for 3 weeks of fermentation time, ( i have never had a bad batch and i am very precise in my sanitation) now all 4 beers taste bad, i think the light skunked them..... the only other thing that changed was i used fermcap in the boil and in the fermentor....

thoughts??? anyone have a white trashbag ruin beer? i think these particular bags were just too thin than the normal thick black yard trash bags i normally use

I think you answered your own question. If you used thin white plastic and the fermenters were in sunlight, they may have gotten skunked.

I've used Fermcap for quite a while and I'm pretty sure it is not a factor in whatever you have going on.

when im fermenting i put all my beers in the spare bedroom with towels wrapped aroudn them...usually dark towels or a really think lighter colored towel....this room does get sunlight will this affect the taste of my beer?

size medium black cotton t-shirts is what I use on my carboys.

What does it taste like?

In the past when I used carboys I preferred paper instead of plastic bags.

I normally use thick black trash bags like for outside, after i tasted these beers and they were bad, i googled to see if there was any listing about white trash bags, white kitchen trash bags ruining beer and i didnt get anything.... so i wanted to make a post to see if anyone else had this experience.... and to also leave record in case someone googles white trash bag carboy cover or something like that.... basically so they would find out that someone else had a problem with it and should use a tshirt towel, or black trashbags over their carboy instead

What's this about white trash? I'm offended.

Seriously, though, plastic will screen much but not all UV and visible light. Given time it will still skunk your beer, especially the UV spectrum which of course you can't see. Is there a reason you can't put your carboys in a closet, or at least toss a thick blanket over them?

This is most likely completely unrelated but I'm throwing it out there.
A lot of kitchen grade (aka not yard or contractor grade) are treated with an anti-fungal compound that can off-gas. This could seriously interfere with yeast activity since yeast is, to a large degree, fungus. It could also just contribute off-flavors on its own. I have zero experience using trash bags with homebrewing but using them with the propagation of other fungi is fairly popular and the number one concern is in obtaining a bag devoid of the anti-fungal treatments.

Food for thought?

TheSeether said:

This is most likely completely unrelated but I'm throwing it out there.
A lot of kitchen grade (aka not yard or contractor grade) are treated with an anti-fungal compound that can off-gas. This could seriously interfere with yeast activity since yeast is, to a large degree, fungus. It could also just contribute off-flavors on its own. I have zero experience using trash bags with homebrewing but using them with the propagation of other fungi is fairly popular and the number one concern is in obtaining a bag devoid of the anti-fungal treatments.

Food for thought?

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They don't call them airLOCKs for nothing.

The definitive home test for skunking is taking a sample and leaving it out in the sun for 10-15 minutes. Cool back to drinking temp and compare with untreated.

I just don't see how a cover, over a glass carboy, could affect the flavor of the beer inside a sealed container.

Have you ever tried skunked beer?

ultravista said:

I just don't see how a cover, over a glass carboy, could affect the flavor of the beer inside a sealed container.

Click to expand...

if light can pass thru into the beer, it can harm the beer. a white plastic trash bag isn't exactly the best cover. if you put your head in a white plastic trash bag (please don't do this, just imagine it), you can most definitely see light. So if you can see light, so can the beer, which isn't a great thing.

OP, if you want to use trash bags, just stick to the 20 mil contractor yard bags. u could tie the carboy up in that and ferment it outside if you wanted to, no light's gonna get thru that. (don't ferment outside, i was just using it as an example).

I've always covered all my carboy's in black plastic yard bags, as McMalty suggests. I lager beer under my house and there's an occasional fungus problem down there when the snow melts, so it's a second line of defense against spores and dust. Never had a problem. Lots of light can pass through a white bag and skunk your beer as others have pointed out, hence the prevalence of brown beer bottles.

So Opherman47, you left your fermenting carboys sitting in sunlight and covered with a white garbage bag?