Milk fat globules enveloped by their biological membrane: Unique colloidal assemblies with a specific composition and structure

Milk fat globules are the natural colloidal assemblies secreted by the mammary epithelial cells to provide lipids and other bioactive molecules in the gastrointestinal tract of newborns. They are also consumed by human adults in food products such as cream and cheeses. These biological entities (about 4 μm diameter) have a complex architecture composed of a core rich in triacylglycerols (TAGs) enveloped by a biological membrane, the milk fat globule membrane (MFGM). Although their utmost importance for infants and their functional and nutritional role in dairy products, milk fat globules remain the least understood aspect of milk. This paper provides an overview of recent knowledge with emphasis on milk fat globule origin, size heterogeneities, fatty acid and TAG composition. The crystallisation properties are reported. Recent studies focusing on the MFGM including characterisation of its composition, probing of its structure, and accumulation of scientific evidence of MFGM nutritional and health properties are also discussed. The unique composition and structure of milk fat globules leading to specific functionalities are highlighted.