Aspartic acid-mediated heat-stressed egg white liquid: Mechanism of controlled thermal aggregation and enhancement of gel properties

To address the decline in gel characteristics of egg white gels during pasteurization heat treatment, the effects of aspartic acid (D) on the thermal aggregation behavior and gel properties of egg white liquid were studied. With the increase in D concentration, the particle size of the protein decreased to 10 nm–100 nm, and the ζ potential changed from negative to positive. During the heating process, the number of positively charged amino acids on the surface of D increases, resulting in a relatively higher energy barrier between protein particles, making it less likely for aggregates to form, which improves the flowability of the egg white liquid. The hardness, viscosity, and chewiness of the egg white gel increased by 69.40%, 60.54%, and 46.65%, respectively. Although the maximum elasticity decreased by approximately 8.39%, the D-mediated egg white enhanced the stability of the gel network structure, improving its resistance to deformation and thereby enhancing the creep recovery characteristics of the gel. Water distribution results indicated that D promotes the conversion of free water in the gel to bound water. Scanning electron microscopy shows that, compared to Control-H, the D-mediated gel structure is more compact and ordered, with uniform pore sizes (<10 μm) and no obvious protein clusters or localized aggregations. This indicates that D effectively alleviates the thermal aggregation behavior of egg white liquid, improving gel performance and providing a theoretical basis for its application as a functional modifier in protein gel systems in the food industry. • Aspartic acid (D)-mediated thermal aggregation of egg white proteins is reduced. • Under thermal stress, D-mediated egg white gels exhibit better gel properties. • D promotes the transformation of free water into bound water in egg white gels. • D reduced ovotransferrin in EWG and prevented the decrease of lysozyme.