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

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