We've all seen a friend getting tipsy on a few beers that contain a mere 10 percent alcohol and then wonder why.The proof of the beer is, in fact, 20.
In the 18th century, proof in alcohol was measured in a very straightforward way. The liquor was "proofed" at the distillery by adding gunpowder and lighting it on fire. If it didn't catch a light, the alcohol content was too weak. If it burned yellow, it was too strong and if it burnt blue, it meant the proof was just right at about 57 percent (which is 114 proof).
A century ago, the American federal government established a standard that quality spirits were "bonded" at 100 proof, in other words 50 percent alcohol. Although the words 'bonded at 100 proof' still appear on certain bottles of old brands, the term doesn't really carry much weight any more.
Over time, taxes and health concerns drove down the average proof. Jack Daniel's whiskey dropped from 90 proof to 80 proof in 2004.
Bartenders still seek out higher proof spirits, because just like fat in food, alcohol delivers flavor and helps to bring out all the tastes of the various ingredients, and deliver the rich mouth feel in those colorful, exotic cocktails.
