Gelation of Egg White Proteins as Affected by Combined Heating and Freezing

Combined effects of preheating (60°C, 0 ～ 30 min) and freezing (– 10 or –20°C, 20 hr) on the gelation of dried egg white induced by reheating (80°C, 30 min) were examined in comparison with those of refrigerating (5°C, 20 hr). Refrigeration consistently induced harder gels, while freezing resulted in either harder or softer gels. Results of soluble protein content, turbidity, SDS-PAGE and gel filtration indicated that the unfolded and aggregated levels of ovotransferrin, caused by the cooperative effects of preheating and freezing or refrigerating, mainly determined the characteristics of gel properties.