Why does sunlight not skunk beer during brewing?

Why when you are outside brewing in the sunshine does the sunlight not skunk the beer there? Isn't it just the hops reacting with UV that causes skunking?

Interesting question. It just seems to happen if the fermenter isn't covered or put in a dark place.

unionrdr said:

Interesting question. It just seems to happen if the fermenter isn't covered or put in a dark place.

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I agree, that or in the bottle. I don't believe alcohol or yeast has to be present to cause this reaction, but possibly..?

What happens is the hop oils get broken down by UV light into about the same chemicals as in skunk spray. Hence the name skunked.

Well first off it isn't beer it's wort til it ferments. Anyway the boil is what breaks down the humulones from the hops into Isohumulones and if you left it unfermented and exposed to sunlight/ultraviolet it will skunk. This takes some time for the sulfur proteins to react with the isohumulones to produce thiol (same stuff a skunk has) a bottle allows for more light to surface area so speeds the process up. The yeast will help to clean up the small amount that you get with exposure during the boil.

I was told to brew in a shady spot and never let the sun shin in the pot, because of skunking. OK, I might be a bit gullible. This will make the brew day easier.

Viator said:

I was told to brew in a shady spot and never let the sun shin in the pot, because of skunking...

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Lol...That quote made my day. Thanks