sunlight

[PaddyMurphy]

how badly does sunlight screw up a fermentation? I just realized I left a couple of carboys uncovered on the kitchen counter at home this morning.

 

[ChaosStout]

how badly does sunlight screw up a fermentation? I just realized I left a couple of carboys uncovered on the kitchen counter at home this morning.

It shouldnt hurt it. If it was summer I would be worried that the heat killed off the yeast(are you still fermenting?) Its beer that hates the light(Hops)

 

[PaddyMurphy]

Yeah, they're still fermenting. I didn't think it would be a problem. Up here in the Frozen North (Maine), I'm thinking the cold shutting down or slowing down the fermentation will be more of a problem.

 

[Brewskii]

The sunlight will not effect the fermentation or yeast. What sunlight ( and many other light sources ) does is attack a weak covalent bond in the humulone molecule from the hops. This molecule will then form a stronger bond to atmospheric sulfur and form a chemical compound similar to that in the musk gland of a skunk.
If you have ever had skunky beer, light is what caused it. It's an off note referred to as "light struck".

 

[Brewskii]

The sunlight will not effect the fermentation or yeast. What sunlight ( and many other light sources ) does is attack a weak covalent bond in the humulone molecule from the hops. This molecule will then form a stronger bond to atmospheric sulfur and form a chemical compound similar to that in the musk gland of a skunk.
If you have ever had skunky beer, light is what caused it. It's an off note referred to as "light struck".

Unless you making mead in which case none of that applies.....

Whoops

 

[Bugeaud]

I would say it shouldn't hurt your mead much if it's only a few days. But I wouldn't try your luck. This reminds me though, of a drink called "Lavish Hags Love Potion." There is no actual full recipe, but from what I compiled of incomplete and nondescript recipes, basically you fill a large glass bottle to the top with blueberries (But not too large or else not enough blueberries will come in contact with sunlight), top off with water, and dissolve as much sugar as you can in there, and give it a good shaking to oxygenate it. Then you leave it to sit out in the sunlight for two weeks. The blue berries must be unwashed or else the natural blueberry yeast will not work.(traditionally made outside and with the lid closed to produce carbonation, but contamination and bottle bombs are no fun, so I would recommend doing it indoors with an airlock, by the window)

 

[malkore]

The thing about sunlight, is heat. As long as its not cooking your fermenters its not a huge deal for mead, but having said that I do all fermentation in a light-shielded room to eliminate 'variables' like that.

 

[PaddyMurphy]

Well, they're both bubbling away happily, so I guess the sunlight didn't hurt.

 

[fongsong]

My winemaker friend mentioned that the light can encourage the growth/developmant of other things (sorry to be so nonspecific, it was a while ago). It won't 'hurt' the fermentation but may lead to off tastes. I don't think that a couple of days will make any difference though

 

[PaddyMurphy]

Fongsong, is that sunlight, or all light?

 

[MedsenFey]

The sunlight will not effect the fermentation or yeast. What sunlight ( and many other light sources ) does is attack a weak covalent bond in the humulone molecule from the hops. This molecule will then form a stronger bond to atmospheric sulfur and form a chemical compound similar to that in the musk gland of a skunk.
If you have ever had skunky beer, light is what caused it. It's an off note referred to as "light struck".

Unless you making mead in which case none of that applies.....

Whoops

Actually some of it applies. Even if there are no hops, wine and meads contain other compounds such as riboflavin that can interact with UV radiation to produce sulfur odors. This is referred to in France as goût de lumière - but the "taste of light" is not a good thing. It is a major flaw. So it is wise to keep your mead protected from sunlight. If light is hitting it during fermentation, that is less likely to be a problem because the fermentation will blow off a lot of sulfur compounds, but during aging and storage, light (esp UV) is not your friend.

I've mentioned this in a couple of other places where this has come up. I apologize for being repetitive, but if any new mead crafters are reading any of these threads later on, they should get the warning.

Medsen

 

[Yooper]

Actually some of it applies. Even if there are no hops, wine and meads contain other compounds such as riboflavin that can interact with UV radiation to produce sulfur odors. This is referred to in France as goût de lumière - but the "taste of light" is not a good thing. It is a major flaw. So it is wise to keep your mead protected from sunlight. If light is hitting it during fermentation, that is less likely to be a problem because the fermentation will blow off a lot of sulfur compounds, but during aging and storage, light (esp UV) is not your friend.

I've mentioned this in a couple of other places where this has come up. I apologize for being repetitive, but if any new mead crafters are reading any of these threads later on, they should get the warning.

Medsen

That's a good reminder.

I've seen lots of posts (especially in the cider forum) where people are assured (incorrectly) that light won't hurt their product, and "only hops cause skunking". While technically true in that it's a different animal (get it? skunk? animal. Nevermind!), it's still possible to ruin a wine/mead/cider by it being light struck.