Study on the Phospholipase in Cow's Milk

Abstract

The phospholipids in cows milk are known to be high in unsaturated fatty acids content. Taking of this point, the authors considered that if these unsaturated fatty acids were lilerated by hydrolysis, they developed the off-flavor of milk by autoxidation. However, no study was reported concerning the presence of phospholipase in milk. The present study deals with the occurrence and the origin of the phospholipase.
(1) The presence of phospholipase was suggested by the increase of lysophosphatidylethanolamine (LPE) during the incubation of milk.(2) Addition of toluene to milk as a preservative resulted in repressing the production of LPE. But free fatty acids and LPE were increased by the incubation of milk-bacteria with milk-phospholipids. These results indicated that the phospholipase was not present originally in milk but was produced by multiplied bacteria.(3) During the incubation of milk, the increase of lysophosphatidylcholine was not observed. Therefore, this enzyme seemed to have specific activity against phosphatidylethanolamine.