L (+) Lactic Acid and D (-) Lactic Acid in Wines

The two stereoisomeric forms of lactic acid have been detected in wines and measured quantitatively by the enzymatic determination of L(+) lactic acid. A chemical determination of the total amount of lactic acid permits the measurement of the D(—) lactic acid by differences. Alcoholic fermentation forms small quantities of D(-) lactic acid while malo-lactic fermentation produces large quantities of the L(+) lactic acid isomer.