Maybe Brent the general managers' opinion doesn't rate any respect but how about Charles Bamforth, PhD, the head of the brewing sciences program at U.C Davis.
Isohumulones, the bitter compounds in hops used in beer, are very sensitive to natural light (artificial light affects them, too, but not nearly as fast). “If light reaches them, they break down very quickly and react with traces of sulfur compounds in the beer,” says Charles Bamforth, chair of the Food Science and Technology Department at the University of California–Davis and a top researcher in brewing science. This process produces MBT (3-methyl-2-butene-1-thiol), which not only smells like skunk, it’s also chemically very similar to the noxious compound in a skunk’s spray. And it’s potent. Some people can detect MBT at concentrations as low as one-billionth of a gram in a 12-ounce beer.
Cans offer the best protection against damaging light waves, and brown bottles rate a close second. “If you have really strong light for a very long time, then even in brown glass, the beer goes skunky,” says Bamforth. “But in a clear glass or a green glass, it’ll happen very, very quickly”—as in a matter of seconds, not hours. Pilsners, traditionally bottled in green glass, are very susceptible to skunking.
