High pressure-induced changes in bovine milk proteins: A review

High pressure (HP)-induced changes in the proteins of bovine milk have become an area of considerable research interest in recent years-, as a result, there is now a detailed understanding of the effects of HP on casein micelles and whey proteins. HP treatment at pressures > 400 or > 100 Mpa denatures the two most abundant whey proteins, alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-1g), respectively The majority of denatured beta-1g in HP-treated milk associates with the casein micelles, although some denatured beta-1g remains in the serum phase or is attached to the milk fat globule membrane; HP-denatured a-la is also associated with the milk fat globules. Casein micelles are disrupted on treatment at pressures > 200 MPa; the rate and extent of micellar disruption increases with pressure and is probably due to the increased solubility of calcium phosphate with increasing pressure. On prolonged treatment at 250-300 MPa, reassociation of micellar fragments occurs through hydrophobic bonding; this process does not occur at a pressure > 300 MPa, leading to considerably smaller micelles in such milk. As a result of HP-induced changes, the size, number, hydration, composition and light-scattering properties of casein micelles in HP-treated milk differ considerably from those in untreated milk. (c) 2005 Elsevier B.V. All rights reserved.