Influence of mastitis on properties of milk. XI. Fat globule membrane.

The effect of mastitis on the milk fat globule membrane of milk samples from individual quarters was investigated. Wisconsin Mastitis Test positive (greater than 20mm) milk contained approximately 10% less milk fat globule membrane material than negative (smaller than 10mm) milk. The lipid portion of the milk fat globule membrane preparation from positive milk contained smaller amounts of phospholipids and larger amounts of cholesterol. Milk fat globule membrane preparations from positive milk had higher aldolase activity and lower xanthine oxidase activity. Dissociated membrane protein prepared from positive milk was resolved into five components by polyacrylamide gel electrophoresis while the membrane protein prepared from negative milk was resolved into three components.