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Tidbits About Alcohol in Beverages

Formation of alcohol in beverages

Alcohol is formed naturally by the fermentation of grains or fruit. Yeast, found everywhere in the environment, uses the sugar in grain or fruit to metabolize it into alcohol (ethanol). Carbon dioxide (CO2) is a byproduct of this reaction, and accounts for the “fizz” in beverages such as beer. The chemical reaction will proceed until the alcohol content is high enough (12-14%) to kill the yeast. This explains why the alcohol content of many wines does not exceed 12-14%, while beers, which range from 3% to 6% alcohol, still contain yeast.

Alcohol content in beverages

Beverages such as “spirits” or “liquors” (e.g., whiskey, vodka, gin) contain a higher alcohol content (e.g., 40%) because they are concentrated by distillation. Distillation is a process that requires heating of the fermented grains and fruit to vaporize the alcohol, which boils at a lower temperature than water. The heated residue is collected as highly concentrated alcohol that is subsequently diluted for human consumption.

Learn more about the vaporization of a molecule.

“Fireproof” Spirits can be expressed as percent alcohol or as “proof,” with proof being twice the percent of the alcohol content. For example, whiskey that is 100 Proof contains 50% alcohol. Before hygrometers could determine the exact alcohol content in a spirit, early distillers could “prove” alcohol content by mixing their distilled liquor with an equal weight of gunpowder. When the mixture was ignited, a steady blue flame proved the alcohol, indicating that the mixture contained 50% alcohol (100 proof!). If the mixture failed to produce a flame, the beverage was considered underproof. Flames that burned bright yellow were indicative of overproof mixtures containing more than 50% alcohol.

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