Proteomic Analysis of the Differences in Heat-Induced Gel Properties of Egg White between Two Chinese Indigenous Duck Breeds

The gel properties of egg white are important functional traits of poultry eggs, yet limited research exists on the utilization of egg whites from local Chinese duck breeds. This study systematically investigated gel properties, ultrastructure, and proteomics of Putian Black Duck (PTEW) and Liancheng White Duck egg whites (LCEW). Results showed that PTEW gels exhibited superior texture properties (hardness, 20.6% higher than LCEW; gumminess, 11.3% higher; chewiness, 11.1% higher; cohesiveness, 7.1% higher) and water holding capacity (7.7% higher). In contrast, LCEW gels were lighter (9.6% higher than PTEW) and whiter (7.3% higher than PTEW). Moreover, LCEW (78 °C) gelation occurred at a higher temperature than PTEW (74 °C). PTEW gels demonstrated a higher relative content of ordered secondary structures (α-helix, 8.6%; β-sheet, 77.3%; 3.7% and 6.2% higher than those of LCEW, respectively) and hydrophobic interactions (56.8%, 9.4% higher than LCEW), enhancing hardness and stability. SEM imaging revealed a denser, more uniform protein network in PTEW. Proteomic analysis identified key proteins, including ovalbumin, ovomucoid, ovalbumin-related protein Y, and ovostatin, as primary contributors to gelation differences. This study offers a comprehensive "properties-structure-substance" understanding of thermal gelation differences between PTEW and LCEW, providing a theoretical basis for utilizing Chinese native duck eggs.