How much light is too much light?

I generally like to let my fermented beer sit in the primary fermenter for a couple of hours in the kitchen (where I bottle) to give any sediment a chance to settle to the bottom of the carboy. I haven't had any issues with skunk beer, but am I testing fate by doing this? I don't have blinds in my kitchen. The sunlight this time of year in my region is mild at this time of the day (17:00 EDT) and it's not in direct sunlight. More like a shaded section of my kitchen.

Topic light skunk homebrew

Category Mac


Your beer will be fine for a few hours in the kitchen.

Skunking is caused by the ultraviolet radiation which provides energy for reactions involving the isomerized hop acids and sulphur compounds in the beer. While there is a small amount of UV radiation emitted by fluorescent bulbs, it's much less than sunlight - 8 hours under a fluorescent bulb is about the same as a minute of sunlight - about 1/500th the amount.

It takes a few minutes of sunlight to skunk a beer, so you'd need to leave the beer under the fluorescent lamp for 24 hours or more, and if your fermentor is semi-opaque plastic bucket it will provide some UV protection, so even longer would be needed.


If it's not direct sunlight, the reaction that produces skunking will take longer, but you're not completely safe. You should probably take steps to limit the amount of light as much as possible in that situation. Maybe throw a towel over it as it sits.

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