Brewers learned long ago that dark bottles protect beer from the light and prevent it from developing a skunky "lightstruck" taste. But it wasn't until 2001 that scientists at the University of North Carolina at Chapel Hill found out exactly what causes that nasty flavor. Certain compounds in in hops, known as isohumulones, break down into free radicals when exposed to light. Those free radicals are chemically similar to the secretions of skunks. And it doesn't take long for the transformation to happen: some beer drinkers will notice the skunky flavor at the bottom of a pint glass that sat in sunlight while they drank it.AHA! I knew about the brown bottles, light, and flavor degradation. But the lime? That's news to me. Those marketing devils!
So why are some beers sold in clear bottles? First, it's cheaper. Second, some mass-produced beers are made with a chemically altered hop compound that doesn't break down. But if you see clear-bottled beers sold in a closed box, chances are it's because the brewer knows the taste will degrade quickly in light. And the tradition of adding a wedge of lime to the beer? That's just a marketing ploy to disguise the skunky flavor.
Amy Stewart, The Drunken Botanist