Effect of Fermentation on L(+) and D(−) Lactic Acid in Milk

Abstract

Total lactic acid and relative amounts of L(+) and D(-) lactic acid in fermented dairy products were investigated by an enzymatic method. Products were regular milk, cultured buttermilk, yogurt, kefir, ropy milk, low fat milk, low fat acidophilus milk, V-medium, acidophilus milk and bifidus milk. The amount of total lactic acid in the fermented products was in the same range (0.6-1.2%) as for lactic acid in fermented products from other countries. In all products L(+) lactic acid was the major isomer formed; 0-10% of the total lactic acid was of D(-) configuration in acidophilus milk. In yogurt, about 400 mg/100 g or about 40% of the total lactic acid was D(-) isomer.