Ethanolic fermentation

The process in which certain yeasts, fungi and bacteria metabolise sugars anaerobically to produce ethanol. Glucose is converted to pyruvic acid, decarboxylated to acetaldehyde, and reduced to ethanol. Synonymous with alcoholic fermentation, it underpins brewing, winemaking, bread-making and bioethanol production. Saccharomyces cerevisiae dominates the process, converting each glucose to two ethanols and two CO₂ with a theoretical yield of 0.51 g ethanol per gram of sugar. Temperature, pH and nitrogen nutrition shape the congener profile — higher alcohols, esters, acetaldehyde — that defines beer, wine and bread flavour; stuck fermentations are the industry’s perennial troubleshooting challenge.