The exact composition of milk varies, depending on a number of factors. The main factor is the animal species; around 85% of milk production worldwide is from cows, with most of the remainder from buffaloes, goats and sheep. Other species account for less than 1% of total milk production.
Within each species, milk composition varies according to a variety of factors. For example, milk from a Jersey cow contains almost twice as much fat as milk from a Holstein. Overall, however, cow’s milk typically contains the following:
- 88% Water ;
- 5% Carbohydrate (lactose) ;
- 4% Lipids (fat) ;
- 3% Proteins, including casein and lactoferrin ;
- Vitamins: B2, B12, A, D and E ;
- Minerals: important source of calcium, magnesium, potassium and sodium.
The energy content for 100g of milk is typically 66 kcal (275 kJ).
Lactose is a slow sugar and therefore is an important energy source for infants. It also helps the body assimilate calcium, which is necessary for developing healthy bones and teeth. The other minerals help maintain correct water balance and contribute to the distribution of oxygen in the blood.
Within the food industry, edible lactose is widely used as a texture- or flavor-enhancing agent. Proteins are important for their nutritional value and also as texture improvers.