Surface protein composition and concentration of whey protein isolate-stabilized oil-in-water emulsions: Effect of heat treatment

摘要

The heat-induced changes in the surface protein compositions and concentrations of whey protein isolate (WPI)-stabilized emulsions were examined. With increasing heating temperature, the amount of adsorbed -lactoglobulin (-lg) increased whereas the amount of adsorbed-lactalbumin (-la)decreased. In emulsions formed with 0.5 wt% WPI, the adsorbed -la almost disappeared from the interface of the emulsion droplets after heating at 121C. With heat treatment at 90 C, adsorbed-lg increased but adsorbed -la decreased in the first 5 min, and then changed slightly with increasing heating time.This change in the proportions of -lg and -la at the interface may have arisen from the displacement of -la from the interface by -lg in the aqueous phase. The addition of NaCl resulted in an increase in the total surface protein concentration during heat treatment, but the competition between -lg and -la at high temperatures was eliminated. The emulsions lost stability because bridging flocculation of the emulsion droplets occurred during heat treatment in the presence of NaCl (>50 mM).