As Oktoberfest celebrations continue through the weekend, the American Chemical Society has provided a critical public service by explaining why beers turn skunky and how one can avoid this misfortune.
Here’s the gist: During the brewing process, hops release iso-alpha acids that provide the bitter flavors that IPA fans love (and correct people, like myself, understand are totally overused). But when sunlight hits these acids, they break down, mix with certain proteins and convert into 3-methyl-2-butene-1-thiol — affectionately known in brewers’ circles as MBT.
“Which is almost indistinguishable from the stuff in a skunk’s behind,” the ACS’s narrator informs us in the video below.
The culprit is light — not heat, as is often assumed — so prevention is simple: Keep your beer in the shade. And please drink responsibly.
Watch the video below to learn more:
This article originally appeared on Recode.net.