We’ve talked before about lightstruck beer and about about how ultraviolet (and even visible light near that end of the spectrum) react with a compound in hops to produce a chemical with many of the same properties as a skunk’s spray.
We’ve also mentioned that green bottles don’t offer much more protections than clear glass, presenting as our evidence the fact that I have never had a Heineken from a bottle that wasn’t skunked.
Well, now there’s some science to back me up.
Rhett Allain, an Associate Professor of Physics at Southeastern Louisiana University, did some experiments with different bottles and some expensive equipment.
The absorption of different wavelengths of light for different colored bottles
As you can see, the green bottles are barely better than clear glass at virtually all wavelengths.
If you love your beer (and unless you like the taste of skunk) get your beer in brown bottles. Even better, a lot of craft brewers are putting their beer in cans nowadays. Even better, pop on down to your local beer-serving establishment and have some beer on draught with your friends. (Heck, have some with your enemies too.)
(via Brookston Beer Bulletin)
I have a friend who actually prefers his beers with that skunky taste. Not overpowering, but likes those easy to drink, slightly skunked, European imports in a green bottle.
Not me, man. I don’t find that skunky taste easy to drink.
He also can’t stand IPA’s… way too much hops for him. But, this is not a put down and I don’t hold it against him. Truly, this friend of mine is a world traveler, enjoys fine wines, and fine food. So how can he be like this about beer? Because as I’ve already pointed out… you can’t be wrong.
Scientists have (relatively) recently discovered the compounds that give “skunked” beer that all-too-familiar aroma.
Isohumulones, one of the compounds that contributes bitterness to beer, decomposes when struck by ultraviolet light and creates 3-methylbut-2-ene-1-thiol (MBT) which is detectable with only a few parts per billion.
Over at khymos.org, a site dedicated to “molecular gastronomy” and the science of cooking, has put together a very nice explanation of the process, including diagrams for those of us who have already been drin…I mean, those of us without a chemistry background.
It’s also apparently not a problem restricted to beer, as olive oil, butter, and milk can suffer the same fate if left in sunlight.
Lightstruck flavor in beer
The moral of the story: Buy beer in brown bottles!
Update: Here’s another excellent explanation of the phenomenon by George de Piro, the Brewmaster at C.H. Evans Brewing Company. While it lacks the really cool chemical reaction diagrams, it does explain why Miller beers, long packaged in clear bottles, don’t “skunk”.