Process by which certain microorganisms (mainly yeasts) metabolize sugars anaerobically to produce alcohols. In this process, glucose is converted to pyruvic acid, which is decarboxylated to acetaldehyde. The acetaldehyde is subsequently reduced to ethanol. A wide variety of substrates can be used to produce alcoholic beverages, e.g. grain for production of beer, and grapes and other fruits for production of wines. However, the constituent sugars must be released from these substrates prior to fermentation. Fermentation can be carried out by endogenous yeasts or by addition of starters. The most common yeasts used in the manufacture of alcoholic beverages are Saccharomyces cerevisiae and S. carlsbergensis . Synonymous with ethanolic fermentation.