Underlying mechanism for the differences in heat-induced gel properties between thick egg whites and thin egg whites: Gel properties, structure and quantitative proteome analysis

Fresh chicken egg whites can be easily categorized into two types, including the colloid-like egg white and the solution-like egg white, which are called thick egg white (TKEW) and thin egg white (TNEW), respectively. In the present study, the heat-induced gel properties of TKEW and TNEW were systematically analyzed and compared. The results showed that TKEW (72.51 °C) had higher temperature of heat denaturation than TNEW (67.01 °C). The texture profile analysis demonstrated that the TKEW gel appeared soft and tough (lower hardness and higher cohesiveness), while the TNEW gel appeared hard and brittle (higher hardness and springiness, but lower cohesiveness). SEM images showed that the TKEW gel exhibited a “mesh structure” with “mountain-like” protrusions and micropores, while the TNEW gel exhibited a “block structure” with a dense section and “rope-head” protrusions. Quantitative proteomic analysis revealed that a higher content of ovotransferrin in TNEW might be the main reason for its lower temperature of thermal denaturation, and a higher content of ovomucin in TKEW might regulate the microstructure of the gel during heating and cause the differences in the gel texture properties. Overall, this study provides insights into the mechanism for the differences of heat-induced gel properties between TKEW and TNEW from the comprehensive “composition-structure-function” perspective, and can give guidance for the regulation of egg white gel properties during its application.