Acetifikation

Acetifikation, also called acetification or acetous fermentation, is the biological oxidation of ethanol to acetic acid by acetic acid bacteria. The process is exploited in the production of vinegar from ethanol-containing substrates such as wine, cider, beer, or fruit must. In this context, acetifikation is the key step converting alcohol into acetic acid, providing the characteristic sour taste and aroma of vinegar.

Main agents are aerobic, gram-negative bacteria of the family Acetobacteraceae, primarily Acetobacter and Komagataeibacter (formerly Gluconobacter and Acetobacter species). They oxidize ethanol to acetaldehyde and then to acetic acid, using oxygen as the electron acceptor. Some bacteria also produce cellulose as a byproduct, especially Komagataeibacter.

Industrial acetifikation occurs in two main formats: surface culture, where a film of liquid remains exposed to air on a wooden or metal surface; and submerged fermentation, where oxygen is efficiently supplied in aerated tanks. Key requirements are sufficient ethanol (typically around 5–12% by volume), adequate oxygenation, and moderate temperatures (roughly 25–30°C). The reaction proceeds until ethanol is depleted or inhibited by increasing acetic acid concentration.

Products are vinegars of various grades and flavors, depending on the starting material and any aging or flavoring steps. In modern industry, submerged fermentation allows rapid production of wine vinegar and other fruit vinegars on a large scale, with pasteurization or filtration used to stabilize the product.

Related topics include acetic fermentation and acetic acid bacteria.