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 (filmjölk), yogurt, kefir, ropy milk (långmjölk), low fat milk (lättmjölk), 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 (.6 to 1.2%) as for lactic acid in fermented products from other countries. In all products L(+) lactic acid was the major isomer formed. Between 0 and 10% of the total lactic acid was of D(−) configuration in acidophilus milk. In yogurt, about 400 mg/100g, or about 40%, of the total lactic acid was D(−) isomer.