Aggregation of bovine β-lactoglobulins A and B on heating at 75 °C

Abstract

The aggregation of β-lactoglobulin (β-lg) genetic variants A and B, isolated from milks of individual cows that were homozygous for each variant, and dissolved in imidazole-HCl buffer containing 0.1 mol L −1 NaCl, was examined using high performance liquid chromatography on a TSK-GEL G4000SW column. The extent of aggregation after heating at 75 °C increased with heating time and protein concentration, and there were marked differences between the aggregation behaviour of the two variants. Below a protein concentration of 5% ( w v ), the aggregation was faster for the B than for the A variant but above 5% ( w v ), the A variant appeared to be more sensitive to thermal aggregation. The conflicting results reported in the literature on the thermal denaturation of β-lg A and B could be explained on the basis of different protein concentrations used by different researchers.