Lactation

Production and delivery of milk to offspring. It is characteristic of living mammals, including egg-laying monotremes.

Breast milk is milk produced by human mammary glands during lactation. Its nutrients and other constituents support the infant while its composition changes with physiological context. It is a biological secretion rather than one invariant chemical mixture.

The mammary secretion supplying water and nutrients to mammalian young.

The liquid fraction after curd separation; it retains lactose, soluble proteins and many dissolved salts.

The fraction remaining after substantial fat removal from milk.

The fat-enriched fraction of milk.

A milk fat globule is a lipid-rich droplet surrounded by an interfacial membrane derived from the secreting cell. Dispersion of many droplets contributes to the physical properties of milk. Fat content and droplet structure are different measurements.^[ref]

A milk protein is a protein present in milk, including caseins and whey proteins. Different fractions have different aggregation and processing properties, so total protein concentration alone does not specify the behavior of the mixture.^[ref]

A whey protein belongs to the milk-protein fraction remaining in the liquid after casein separation under the specified conditions. Heating can change protein structure and association, making the separation method part of the operational definition.^[ref]

Milk chemistry concerns the constituents and transformations of milk. Fat droplets, dissolved small molecules and protein assemblies contribute differently to its behavior. Separation and processing make these differences experimentally visible.^[ref]

Cow's milk is the milk secretion of cattle. Its fat, protein and dissolved constituents form a dispersed mixture whose composition varies among animals and across lactation. A typical composition is therefore a description of a sample population rather than a fixed chemical formula.^[ref]