Fermentation and Distillation

Fermentation is the production of alcohol from sugars through the action of yeast. It forms the basis of all alcoholic beverages. Fruit plus yeast equals fermentation because fruits naturally contain sugar. Cereal grains contain starch which must be converted to sugar by malt before fermentation can begin. Yeast has a limited tolerance for alcohol. When the concentration reaches a certain percentage (15% is possible, but the standard for wine is about 12%), the yeast dies and fermentation ceases.

Distillation is the evaporation and condensing of alcohol vapors to produce beverages with alcohol content higher than 15 percent. It was perhaps first used in Arabia around AD 800 and introduced into Europe in about the 10th century. In the US, distillation began on a large scale at the end of the 18th century.

Proof is the alcohol content of a distilled beverage and is twice the percentage of alcohol by weight. 90 proof whiskey is 45 percent alcohol.


Beer is made by adding barley malt to other cereal grains. Hops are added with yeast to give beer its flavor. Lager uses a type of yeast that settles to the bottom of the mash to ferment. Ale uses a top fermentation yeast, warmer fermentation temperature, and more malt and hops. Light beer is fermented longer at a cooler temperature. More sugar is converted to alcohol, then water is added. The result is a beverage with similar alcohol content but less sugar and fewer calories than regular beer.

Malted Barley Hops
Malted Barley Hops


Alcoholic beverages have been consumed for thousands of years, at least as far back as 6400 BC (beer and berry wine). Grape wine has existed for over 2,000 years. Mead may date back to the Paleolithic Age around 8000 BC. Beer was consumed by Native Americans at the time of Columbus's landing.

Wine is made from fermented grapes. Most wines contain about 12% alcohol. There are generic wines and varietals which are determined by the type of grapes and flavor, red and white wines, sweet and dry wines, sparkling wines, and fortified wines with alcohol content nearly 20 percent.

Grain neutral spirits are clear, tasteless, nearly pure alcohol (190 proof) produced by distillation. Grain neutral spirits are used to make various beverages such as gin and vodka. In gin, the distillate is filtered through juniper berries and then diluted with water. Vodka is a mixture of grain neutral spirits and water.

Whiskey is a distillate of fermented barley. An early US distiller from Bourbon County, Kentucky gave bourbon its name. Whiskey is usually aged for at least 2 years.

Liqueurs or cordials have alcohol content of about 20 to 25 percent. They are originally made from brandy mixed with flavorings from herbs, berries, or nuts. Now, they are typically made from flavored, diluted grain neutral spirits.

Blood Alcohol Concentration

Alcohol metabolizes in the liver at about 1/4 to 1/3 ounces per hour. The standard drink has about 0.5 ounces of pure alcohol or about 12 ounces of beer, 4 ounces of wine or 1 ounce of 100 proof spirits. Women tend to be more susceptible than men to the effects of alcohol after consuming the same amount. Alcohol dehydrogenase (a stomach enzyme) is more active in men, so women absorb a greater proportion of the alcohol they drink. Also, alcohol is stored in body fat, and women tend to weigh less but have a higher proportion of body fat. Check out the following blood alcohol concentration calculator: Blood Alcohol Concentration Calculator

*From the book, Drugs, Society & Human Behavior, 14th edition, by Carl L. Hart and Charles Ksir.

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