Nanosilver–Titanium Dioxide-Enhanced Chitosan Composite Film for Prolonged Egg Preservation: Antibacterial and Antioxidant Mechanisms

Eggs, a staple and vital food in daily life, present a significant challenge regarding preservation. To extend the shelf life of eggs, this study developed a chitosan-based composite coating for egg preservation and antibacterial activity. The hydrophobicity and preservation effects of this chitosan composite film were investigated. The experimental results demonstrated that the chitosan composite film exhibited excellent hydrophobic properties. In tests evaluating the preservation performance, eggs coated with the chitosan composite film showed superior results across several parameters. Specifically, the weight loss rate of eggs coated with the chitosan film increased the least over time. Weight loss at 49 days was 26.70% lower in the coated group (7.99%) compared to the uncoated group (10.90%), indicating that the composite effectively sealed the micropores of the eggshell, preventing moisture loss. Moreover, Haugh unit values were higher overall in the coated group than in the uncoated group and were significantly higher on days 14 and 49 than in the uncoated group. The yolk index of the coated eggs exhibited a smaller decline trend and was significantly higher than the control group at specific intervals. The yolk index at Day 49 was significantly higher in the coated group (0.22) than in the uncoated group (liquefaction). Additionally, the pH of egg whites in the coated eggs showed minimal increases over time. Total bacterial count tests revealed that the composite film developed in this study provided antibacterial effects on both the eggshell surface and internal content. Antioxidant assessments of the egg yolk indicated that the composite coating significantly enhanced total antioxidant capacity, superoxide dismutase activity, and slowed down total malondialdehyde production, thereby inhibiting lipid oxidation in the yolk. This study offers a promising approach for improving egg preservation and provides valuable insights for broader applications in food preservation technologies.