If your beer tastes or smells like it was filtered through a skunk’s butt, it is probably due to the beer being “skunked” or named Heineken or Rolling Rock (zing!). Almost nothing makes for a worse beer experience than getting a mouthful of rancid beer water when you were hoping for hoppy deliciousness. But why does this happen? WHY!
Let’s get this out of the way first: temp changes don’t skunk beer. It’s not recommended to subject a beer to extreme temperature shifts, but you aren’t going to taste the back end of Pepe Le Pew because of it. Skunking comes from beer that is exposed to sun or fluorescent light, which is why it’s technically referred to as “lightstruck.” A chemical reaction causes the beer to produce methyl mercaptan, also found in what skunk’s spray, hence the similar odor.
Many breweries still insist on using clear (Corona) or green (Heineken) bottles, which do little to protect the beer. Even a glass of beer left out in the sun can start to exhibit the effects of “skunking” fairly quickly, so clear/green bottled beers sitting on shelves for weeks of sun or fluorescent light exposure are sure to skunk it up before you get them. Avoid beer in clear or green bottles!
Brown bottles work far better and are the predominant bottle choice for brewers. Better still are cans, which are seeing a growing popularity among craft brewers for the very reason of keeping the beer in the dark. Know that canned beer isn’t the indicator of cheap beer that it used to be. It’s a sign that the brewers of that craft beer care enough to fill you full of quality brew, not skunked out stank. So buy smart, hibernate your beer in a cool, dark place and enjoy it fresh!
You can read a more sciency chemist explanation of lightstruck beers here: Beer Sensory Science – Lightstruck