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The science of skunky beer (and how to prevent it)

There’s nothing worse than reaching for a cold beer, taking that first sip and realizing your beer’s been skunked. Skunking is a chemical reaction that causes an awful, bitter taste. Why does it happen? Quick answer: It's all about light. (Video: Reactions/American Chemical Society via YouTube)
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With October just a few days away, beer lovers are buzzing in anticipation. But there's bad news: Even though it's cool and breezy out, your beer can still get skunked.

Although many think that "skunking," or the phenomenon of beer developing a putrid taste and smell, is caused by heat, it's actually caused by light exposure. The American Chemical Society explains the process in their latest video, above.

When hops are boiled down to make beer, they release chemical compounds called Iso-Alpha Acids. They're bitter on their own, but when exposed to sunlight they break down and interact with other molecules in the beer to produce a molecule that's almost identical to the one in a skunk's smelly spray.

And it's so strong that if you put one eyedropper of the chemical in an Olympic pool full of beer, you'd change the taste -- which would surely ruin your boozy backstroke.

Hot beer can get stale more quickly, but it won't skunk. It's all about that sunshine, which is why most beers are sold in dark glass containers or solid aluminum cans. If a beer comes in a light glass bottle, it probably uses a chemically modified form of hops instead of the real thing -- but skunking can still occur. So whatever your brew of choice at Oktoberfest, stay in the shade.