Mechanism on the regulation of liquid egg white protein foam behavior by heat treatment

In response to the issue of pasteurization-induced degradation of the functional properties of liquid egg whites (LEW), this study explores the patterns and mechanisms of the effects of heat treatment on the overrun and drainage rates of whipped liquid egg whites (WLEW). Our findings indicate that the overrun of the WLEW subjected to a 90 min heat treatment at 60 °C was markedly enhanced by 11.43 and 73.30 % relative to the control group (CK) and the 5 min heat-treated group, respectively. Concurrently, the drainage rates were significantly reduced by 64.02 and 37.93 %, respectively. Microscopic analysis and dynamic foam property assessments revealed that the 90 min heat-treated group demonstrated the most stable foam structure. Furthermore, the textural attributes (firmness, consistency, cohesiveness, and viscosity) of this group were substantially improved by 133.05, 125.02, 143.41 and 101.61 %, respectively, when compared to the 5 min heat-treated group. Notably, the observed trends in surface tension, interfacial film's elastic modulus, and protein particle size paralleled those of the overrun. Post-heat treatment, an increase in free sulfhydryl content, a decrease in fluorescence intensity, an elevation in the proportion of random coil structure, and an increase in surface hydrophobicity were observed. These results suggest that the alterations in protein particle size and interfacial properties, consequent to thermal modifications in protein structure, are the principal factors behind the observed variations in foam properties. This study, therefore, provides an effective strategy and valuable theoretical insights for the production of high-quality WLEW products.