Define 'lightstruck'

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Define 'lightstruck'

Post by alepale »

In some literature, I read that you can get a lightstruck taste (not good)

What does lightstruck mean? How do I know if my beer is lightstruck?

How to avoid getting this apparently bad taste?

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Re: Define 'lightstruck'

Post by alepale »

Ok I found the answer of how it happens, but how can you tell the difference in taste?

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Re: Define 'lightstruck'

Post by D_Rickards »

You can smell it and taste it as the hops flavours are either gone or worse smell like skunk. Another term for light struck is "skunky".

Here is a pretty good article on the subject.

It can happen to any beer exposed to light (ie - in any bottle) and is more likely to happen to beer in clear bottles than amber bottles. It can't happen to canned or kegged beer because UV light can't get to that until the beer has been poured.


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Re: Define 'lightstruck'

Post by XXXXX »

I've had it happen when I left a glass carboy of fermenting unprotected. It was not even in direct sunlight.

The result is that it tastes (and smells) skunky.

It was a learning experience. I didn't think it'd occur unless it was direct sunlight, and I was wrong.

If you're worried about it, put a black garbage bag around the fermenter to block out ambient light.

As mentioned, amber or green bottles help slow it down. An opaque vessel or barrier will prevent it altogether.
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Re: Define 'lightstruck'

Post by Wingeezer »

There was an interesting test done by Homebrewer and podcaster James Spencer and his buddy Steve, whereby they sat out in the garden on a sunny day with some Sierra Nevada Pale Ale to check out the affect of UV on beer. The video is on their video podcast - maybe a year or so back.

They sampled a glass full that had been left sitting in the sun, then drank another sample that had also been poured into a glass but was shield from the sun by a bag (paper bag or black garbage bag, I don't recall.) Finally they poured a third sample from a Sierra Nevada bottle that had also been in the sun - I think Sierra Nevada bottles are brown.

I believe the beers had only been exposed for about half hour and it wasn't even a completely sunny day - mix, sun & clouds.

Unless they were exaggerating, the difference was dramatic. The beer protected by the bag and that in the original bottle were fine but the glass full that had been left fully exposed to sun was completely undrinkable.

According to Steve Spencer, the chemical produced by the reaction of the UV on the hop content of the beer is in fact the same as produced by a skunk, hence the nickname "Skunky."

I was amazed how quickly the beer could "turn." I watched the video with my son in law and we decided to repeat the test ourselves at some point!

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Re: Define 'lightstruck'

Post by Venari »

I suppose I should put a blanket or something around my glass carboy. I have a pumpkin brew sitting in a glass carboy (is it carboy, or carbouy for us canadians?) which is currently in a crawlspace, but the door to that crawlspace is open (can't close it, my mother is something of a minor hoarder and wont throw out anything that might come in useful some day, which makes for lots of clutter).

The only light getting into that crawlspace is from the hallway lightbulb, but the carboy itself isn't getting lit up directly. Is that enough, or should I cover it up? Aw heck, i'll go cover it right now anyway.
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Re: Define 'lightstruck'

Post by Mr_Tastyfish »

I use clear glass carboys for fermentation, and have never had a batch go "skunky". I only cover my carboys if it's in an attempt to regulate the temperature (either a blanket or wet t-shirt). They're kept in a windowless room, so the only light they ever see comes from electric light bulbs. Unless you're using bulbs specifically designed for either reptile basking lights, or plant grow lights, ordinary household bulbs just don't give off the kind of UV wavelengths that would skunk a beer.

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Re: Define 'lightstruck'

Post by Goulaigan »

I believe prolonged exposure to fluorescent lights will cause this as well, which is why I can't understand why the lcbo keeps beer exposed under fluorescent lights. Brown/amber bottles are the best for keeping out the light, green I find are not so good. Heineken and moosehead are not supposed to be skunky. If you want to do an easy experiment just grab a moosehead in a can and a 6 pack in bottles, and taste them in succession. I never liked moosehead until I tried it in a can, and still am not a big fan but can vs bottle is night and day. My biggest dissapointment was paying a damn good price for a Saison dupont and discovering that it tasted like a skunks butt. Good for certain vices but never good in beer... Why breweries use greeen glass I'll never know

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