Studies on the change in the properties of the fat globule membrane during the concentrating of milk

Some aspects of the chemical composition of the milk fat globule membrane during lactation

The protein, phospholipid and neutral lipid composition of a deoxycholatesoluble fraction (DOCM) from bovine milk fat globule membrane (FGM) was determined, at intervals during lactation, in 3 cows maintained at a constant level of food intake. It was suggested that the appearance of free fat in washed cream during the first 2 days post partum was related to membrane stability in colostral secretion. Differences between the cows in DOCM yield (mg/100 g cream lipid) and composition were greatest during the first 25 days post partum. DOCM yield increased markedly as lactation proceeded in one animal, and this was thought to be due to a decrease in globule size. Variation in DOCM composition was principally due to an alteration in neutral lipid content. There were few differences, however, between the quantities of phospholipid and protein in DOCM for all 3 animals, and similarly the percentage composition of the major DOCM phospholipids varied little, phosphatidyl choline being the predominant phospholipid.

The influence of various treatments on the drainage of continuously made curd

The effect of layer thickness and orientation, and of pressure, temperature, and disturbance on the drainage rates of continuously made curd were determined. The effects of heat treatment of the milk and adjustments of its pH were briefly examined. An increase in temperature of the curd caused the expected increase in drainage rate as did also the application of pressure. Vertical layers of curd drained more quickly than almost horizontal layers, and keeping curd in whey retarded its drainage. The effects of pH change over the narrow range of interest (6·1–6·5) were relatively small. Pasteurization of the milk had no effect. Disturbance of the curd had the most pronounced effect in increasing its rate of drainage.