The fat content and its type are of considerable commercial and nutritional importance to the dairy industry.
Biologically, due to the high percentage of carbon in fats, they are ‘stored’ nutrients with the highest energy or calorific value of all food constituents.
Milk fat occurs in the form of droplets or globules, surrounded by a membrane and emulsified in milk serum (also called whey).
The fat globule membrane acts as the emulsifying agent for the fat suspended in milk. The membrane protects the fat from enzymes and prevents the globules coalescing into butter grains.
The fat globules (called cream) separate after prolonged storage or after centrifugation. The fat globules float on the skim milk.
Homogenization of milk so finely divides and emulsifies the fat globules that cream separation does not occur even after prolonged standing.
About 98% of milk fat is a mixture of triacyl glycerides. The partial glycerides (diglycerides and monoglycerides) and free fatty acids are probably partly left over from the biosynthesis process.
Fat in milk
