There are three kinds of pure milk, among which skim pure milk has 68 calories per 200 ml; Semi-skimmed pure milk has 98 calories per 200ml of calories; Full-fat pure milk with 134 calories per 200ml.

The content of protein in pure milk is 2.8%-3.3%, which is mainly composed of 79.6% casein, 1 1.5% whey (white) protein and 3.3% lactoglobulin, and a small amount of other protein, such as immunoglobulins and enzymes. Casein combines with calcium and phosphorus in pure milk to form casein colloidal particles, which exist in milk in the form of colloidal suspension.