Enzyme and thermal induced transition of egg white proteins from dense-globular to random coil triggering uniform...

For natural egg white protein (NEWP), heat-driven unfolding of its compact, globular structure exposes hydrophobic moieties, thereby promoting excessive aggregation and resulting in visually apparent thermal instability. In this study, a combined thermal-enzymatic treatment was used to induce the formation of uniformly dispersed aggregations with excellent thermal stability. The physical and chemical properties, microscopic morphology, and molecular structure were explored to reveal the formation mechanism of uniformly dispersed particles and the structure-activity relationship. Results indicated that preheating treatment facilitated protein unfolding, leading to the exposure of hydrophobic regions and enzymatic cleavage sites, thereby promoting the formation of NEWP aggregation with low atomic density and high susceptibility to enzymatic hydrolysis. Subsequently, thermal clusters were hydrolyzed by protease into more uniformly dispersed peptide aggregation, displaying micro size and low-bulk-density properties. Under higher thermal treatment (80 °C), the protein hydrolyzed fragments showed looser atom density, more random coil structure and better thermal stability. These results verified that the transition of NEWP from dense-globular to random coil structure, was beneficial for weaker inter-particle hydrophobic interaction. This work systematically investigates how low-bulk-density NEWP modulates the depolymerization-reassembly equilibrium of protein conformations after thermal treatment, yielding valuable insights for engineering EWP-based products with improved thermal stability.