Abstract: Vinegar having an acetic acid concentration higher than 20 percent weight by volume is produced in a submerged fermentation by maintaining the temperature of a fermenting broth at 27.degree.-32.degree. C. until the acetic acid concentration of the fermenting broth (after the initiation of fermentation) reaches 12-15 percent weight by volume. Then the temperature of the fermenting broth is lowered by 0.5.degree. C. to 2.degree. C. Fermentation is continued at the lower temperature until the concentration of acetic acid increases by between 0.05 to 2 percent weight by volume. At this time, the temperature is again reduced by from 0.5.degree. C. to 2.degree. C. The fermentation is continued, with subsequent temperature reductions of from 0.5.degree. C. to 2.degree. C. each time that the concentration of acetic acid in the fermentation broth increases by 0.

Abstract: A finished vinegar having an acetic acid concentration higher than 20 percent weight by volume is produced by repeating a fermentation cycle wherein a broth is fermented at 27.degree.-32.degree. C. in a 1st submerged fermentation tank by a continuous batch process, and, when the acetic acid concentration of the fermenting broth reaches 12-15 percent weight by volume, the large part of the fermenting broth in the 1st fermentation tank is withdrawn and charged in a 2nd submerged fermentation tank. The 1st fermentation tank is recharged with a mash and the fermentation of the fermenting broth in the 2nd tank is continued under aeration while lowering the temperature of the fermenting broth in such manner that the final fermentation temperature does not fall below 18.degree. C. and the lowering temperature does not become higher than the temperature once lowered.

Abstract: Vinegar having an acetic acid concentration higher than 18 percent weight by volume is produced in a submerged fermentation by maintaining the temperature of the fermenting broth after the initiation of the fermentation at 27.degree.-32.degree. C. until the acetic concentration of the fermenting broth reaches 12-15 percent weight by volume and thereafter maintaining the temperature of the fermenting broth at 18.degree.-24.degree. C.