Effect of heat treatment on the antigenicity of bovine α-lactalbumin and β-lactoglobulin in whey protein isolate

The effect of heat treatment on the antigenicity of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) in whey protein isolate (WPI) was investigated at temperatures in the range of 50–120°C for times from 0.5 to 30 min. The antigenicity was determined by an indirect competitive enzyme-linked immunosorbent assay. The heat denaturation of α-LA and β-LG was revealed by SDS-PAGE electrophoresis. The antigenicity of α-LA and β-LG increased with increasing temperature from 50 to 90°C and the highest antigenicity of α-LA and β-LG was detected at 90°C. However, above 90°C the antigenicity of both proteins showed a remarkable decrease. When treated at 120°C for 20 min, the antigenicity of α-LA decreased below the initial value of the untreated sample. The antigenicity of α-LA and β-LG in WPI can be decreased at certain heat temperature and time.