Pressure-Induced Denaturation of β-Lactoglobulin in Skim Milk: Effect of Milk Concentration

Abstract

The effect of milk concentration (10-40% TS) on the kinetics of the pressure-induced denaturation of β-lactoglobulin (β-LG) was studied. The denaturation was found to be a second-order process at all milk concentrations and pressures. There was a change in pressure dependence of the rate constants for denaturation at about 300 MPa, and this effect became more pronounced as the milk concentration increased. At pressures ≥300 MPa, a small effect of milk concentration was observed, with small decreases in the rate of denaturation as the milk concentration was increased above 20% TS. This was attributed to the lower pH as the milk concentration was increased. In contrast, at 200 MPa, β-LG denaturation was markedly retarded as the milk solids concentration was increased. This was attributed to the increased lactose concentration at higher milk concentrations. This would promote β-LG dimerization at this pressure and this would stabilize the β-LG to denaturation.