Kinetics of milk fat globules lipolysis and destabilization
Résumé
Bovine milk fat globules are subjected to the action of lipolytic enzymes during storage and during milk transformation processes. The products of lipolysis, free fatty acids, partial glycerides and lysophospholipids contribute to final product sensory and physical properties. The extent and the kinetics of lipolysis are conditioned by several parameters among which the state and the surface of the enzyme/substrate interface are determining.
In its native state the bovine milk fat globule is protected by a trilayered complex membrane resulting from the mechanism of exocytose of the globule from the epithelial cells of the mammary glands. This membrane, as long as it is not disrupted, constitutes a physical barrier which limits the access of lipases to the milk fat substrate. The extent of this protective effect against the endogenous lipoprotein related lipase in comparison with other lipolytic enzymes of variable specificity has not been comprehensively described in literature. The objective of our study was to explore the reactivity of native milk fat globules subjected to endo- or exogenous enzymes in vitro. The kinetics of lipolysis of this supramolecular structure was studied. Particular attention was given to the kinetics of milk fat globule destabilization in response to the action of various types of enzymes (lipase, phospholipase or
protease).