Synergistic enhancement of gelatin-chitosan films with vanillin Schiff base and ZnO for effective strawberry preservation

This study successfully developed an innovative chitosan/gelatin/vanillin-Zn²⁺ food packaging film (CGV-Zn²⁺) for the preservation of strawberries. To overcome inherent limitations in polysaccharide-based films, we employed a dual modification strategy: Schiff base formation between vanillin aldehyde groups and chitosan/gelatin amines, and Zn²⁺ complexation from acid-treated ZnO nanoparticles. Structural characterization revealed that Zn²⁺ chelation significantly improved the mechanical properties and cross-linking density, while the aromatic structure of vanillin provided exceptional UV-blocking efficiency. The composite films exhibited enhanced water resistance, reduced oxygen transmission, and potent antimicrobial activity against E. coli and S. aureus. When applied to strawberry preservation at 4 °C, CGV-Zn²⁺ films maintained fruit firmness, minimized weight loss, and preserved antioxidant capacity over 15 days through combined barrier effects and antimicrobial action. Our research indicated that CGV-Zn²⁺ composite films held significant potential as an alternative to conventional plastic-based food packaging materials, demonstrating considerable efficacy in fruit preservation applications.