Alcohol

The alcohol used in wines, beers and spirits is ethanol.

Where does it come from?

Alcohol is produced by fermenting fruits, vegetables or grains. The anaerobic respiration of yeast makes the sugars in fruit juice or the malt from barley convert into alcohol.

Different countries have different alcoholic specialities e.g. France and wine; Russia and Vodka; and Czechoslovakia and their pilsner.

One of the earliest mentions of wine making is from an Egyptian papyrus dated 3,500 BC. The making of alcoholic spirits like gin and brandy only started some one thousand or so years ago.

Chemistry

When a person drinks an alcoholic beverage, about 20% of the alcohol is absorbed in the stomach and about 80% is absorbed in the small intestine. One of the most rapid affects of alcohol is on the central nervous system (CNS), which controls a range of vital body functions including speech, muscles, sense organs and sweat glands.

Usually the CNS receives information from organs such as the eyes and ears, analyses it and then responds, perhaps by contracting a muscle. However, alcohol impairs our CNS functioning which, in turn, causes the usual symptoms of being drunk. These include disturbed balance, slurred speech, blurred vision, excess sweating and the dulling of our sensation of pain.

Alcohol also affects the outer layer of the brain (the frontal cortex) that is concerned with conscious thought. This is why people under the influence of alcohol often lose their inhibitions and dance on the tables.

Production

Yeast is added to solutions containing sugar e.g. grape juice. The mixture is then left to ferment for several weeks in a container that excludes air but allows carbon dioxide to escape. When the alcoholic content of the mixture is about 15% the yeast becomes inactive and the process stops. Stronger alcoholic solutions are made by fractional distillation of the fermented products.