Effect of pH on Malo-Lactic Fermentation in Wine

Malo-lactic fermentation was induced by inoculation with Leuconostoc oenos ML 34 of red wine which had been adjusted to seven different pH values between 3.1 and 3.8. The resulting malolactic fermentation rates were directly proportional to these initial pH9s. Malo-lactic fermentation brought about pH increases as great as 0.2 unit; the increases were greater at the higher initial pH values. The decreases in titratable acidity were greater in the middle of the range of initial pH9s. Of the lactic acid produced by malo-lactic fermentation, most was of the L(+)-isomer. Greater diacetyl, acetoin, and volatile acidity were associated with malo-lactic fermentation, but there was no clear effect of pH on their production by the bacteria.