I didn't realize that whisky, once opened, doesn't last forever. Maybe you did already, but I have to thank Belgian whisky writer François Monti for opening my horrified eyes.
Vodka, whisky, brandy, whatever, will not turn into vinegar like wine. It will never go bad in the sense that it will make you sick or be undrinkable if you just want to get buzzed. But it will lose its flavor and charm, and for me that's the point of drinking.
Most unopened bottles of liquor will last for years, possibly decades. Indefinitely, no. If you buy a museum-piece bottle of Calvados or Scotch from the 1950s, you might be disappointed, unless the liquor spent most of that time sleeping in barrels at the distillery. It's important to know when the booze was bottled.
The question is, how long will an open bottle of booze last before it goes downhill?
It's all a question of oxidation. When a bottle is first opened, a little oxidation might actually help it, by smoothing out the flavor. But the booze will gradually lose its freshness and complexity. There's a lot of debate in this forum post I found on whisky.com about exactly when the tipping point occurs, and there are anecdotes, but not any science that I could find.
Storage matters: you should store your booze in a cool, dark area. Sunlight is its enemy more than heat.
Monti says that in his home in Madrid, bottles of booze only last about 18 months, once opened. In cleaning out my whisky cabinet in much cooler San Francisco, I'm discovering that I have more leeway, maybe 2 1/2 years. But sure enough, the last glass of one of the best Scotches I've ever had, that I opened about 4 years ago, was disappointing, and I wish I had drunk it earlier.
Monti also believes that the oxidation accelerates as you have less liquid and more air in the bottle.
Monti says that when he goes to a bar, he never orders a super-expensive dram from an opened bottle, even if he really wants to try it. The area above a bar where those bottles are stored is about as bad for long-term preservation as you can get: fairly hot, with frequent bright light. He says he likes to order a quality whisky that he knows the bar will cycle through fairly quickly. (A few of my favorites in this category: Glenmorangie, Highland Park, Ardbeg.)
I hope you knew all this already. But my friend Jeff, who collects Scotch in sultry Tampa, Florida, didn't know; he was just as horrified as I was, because now he's got a lot of drinking to do. As do I. And maybe you too. Open that liquor cabinet wide and see what's hiding back there. And get to work.
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The idea that more air in the bottle will cause more oxidation is weird since the amount of air able to make contact with the alcohol will be exactly the same for most of the bottle.
ReplyDeleteI understand your thought process but it is, in fact, a complex combination of chemical reactions and mass transfer phenomenon. As the oxygen "oxidizes" the liquor, a reaction occurs by which the oxygen in contact with (actually diffusing into) the surface of the liquid. When the oxygen reacts, it depletes from the area near the surface, thus more oxygen diffuses into that space to reestablish equilibrium. With more air in the bottle, this process has a larger driving force. Next, even if the same rate of oxidation was occurring in two bottles, for example, one 9/10 full and the other 1/2 full, the fact that there is less liquor means that for every reaction of oxygen with the liquid, the concentration of affected liquor would be much higher in the 1/2 full bottle. These two phenomenon (which have been confirmed empirically in systems other than liquor) validate the statement that the more booze in the bottle, the less it is effected by storage.
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