Effect of high-pressure and heat treatments on denaturation and aggregation of bovinewhey proteins: influence of sulfydryl-modifying agents and glycerol

摘要

This work is focused on the effect of high pressure treatment on denaturation and aggregation of whey proteins, and on the influence of sulfydryl-modifying agents and glycerol on their denaturation. The degree of denaturation of [3-lactoglobulin, a-lactalbumin, lactoferrin and IgG was determined using immunochemical techniques and that of lactoperoxidase using an enzymatic technique. Using SDS-electrophoresis, we observed that pressure treatment of [3-lactoglobulin in buffer induced its aggregation whereas this effect was not observed for the other proteins studied. Furthermore, pressure treatment of whey produced disulfide-bonded aggregates of whey proteins. Baroresistance of all the whey proteins was much higher when milk or whey was treated in the presence of /V-ethylmaleimide and KI03 except for (3-lactoglobulin, which was completely degraded when treated with KI03. Pressure treatment of whey in the presence of glycerol increased resistance of all the proteins studied. The results obtained allow elucidation of the mechanism of pressure-induced denaturation of whey proteins.