Acetic acid fermentation
Japanese: 酢酸発酵
The reaction in which acetic acid bacteria oxidize alcohol into acetic acid. An aerobic fermentation essential for vinegar production.
Acetic acid fermentation is the reaction in which acetic acid bacteria oxidize alcohol into acetic acid. Unlike alcoholic or lactic acid fermentation, it is aerobic—requiring oxygen.
Vinegar production is the direct product of this reaction. For rice vinegar, rice is first saccharified, yeast performs alcoholic fermentation, and finally acetic acid bacteria convert the alcohol to acetic acid—a three-stage microbial relay.
In miso and soy sauce brewing, however, acetic acid bacteria are unwelcome. Along with film-forming yeasts, they appear when the surface is exposed to air. The same microbial activity can be ally or adversary, depending on the context.