The Milk Composition section describes the chemical and physical properties and effects of pasteurization on the compounds in milk. A brief overview of the variation in milk composition is provided below as an introduction to this section. Topics covered are:

Carbohydrate (Lactose) Fat Protein Vitamins and Minerals Enzymes Literature Related to Milk Composition

Unless otherwise stated, the information presented in this website refers to cow's milk. In general, the gross composition of cow's milk in the U.S. is 87.7% water, 4.9% lactose (carbohydrate), 3.4% fat, 3.3% protein, and 0.7% minerals (referred to as ash). Milk composition varies depending on the species (cow, goat, sheep), breed (Holstein, Jersey), the animal's feed, and the stage of lactation. Although there are minor variations in milk composition, the milk from different cows is stored together in bulk tanks and provides a relatively consistent composition of milk year round in the U.S.