Fermentation

Article By:

Van Niel, Cornelis B. Hopkins Marine Station, Pacific Grove, California.

Last reviewed:November 2021

DOI:https://doi.org/10.1036/1097-8542.253100

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• Fermentation, published June 2014:Download PDF Get Adobe Acrobat Reader

An enzymatic transformation of organic substrates, especially carbohydrates, generally accompanied by the evolution of a gas. Fermentation is a chemical transformation of organic substrates, especially carbohydrates, to alcohol or organic acids, typically involving the production of a gas, such as carbon dioxide (CO₂) or hydrogen gas. It is a physiological counterpart of oxidation, permitting certain organisms to live and grow in the absence of air. Fermentation is used in various industrial processes for the manufacture of products such as alcohols, acids, and cheese by the action of yeasts, molds, and bacteria. The best-known example is alcoholic fermentation, in which sugar is converted into ethyl alcohol (ethanol) and carbon dioxide (Fig. 1). This conversion, chemically represented by C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂, was established by J. L. Gay-Lussac in 1815. See also: Carbon dioxide; Distilled spirits; Ethyl alcohol; Food; Food fermentation; Food manufacturing; Food microbiology; Sugars (sweeteners)

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