A high strength, breathable, water resistant chitosan-gelatin composite film modified by tannic acid-synergistic ZIF-8 for blueberry preservation

The growing consumer demand for fresh fruit accelerates the advancement of fruit preservation packaging technology. Functional packaging materials, incorporating natural active substances and nanomaterials, offered a foundation for effective preservation. While traditional nanomaterials, predominantly solid in nature, failed to provide adequate channels for material exchange necessary to meet the respiratory requirements of fruits. In this study, porous metal-organic framework zeolitic imidazolate framework-8 (ZIF-8) was synthesized and combined with tannic acid to construct respiratory channels, which were subsequently incorporated into chitosan/gelatin/polyvinyl alcohol composite films. The results demonstrated that ZIF-8@tannin strengthened the cross-linked network structure of the polymer, thereby enhancing the biocompatibility, thermal stability, mechanical strength, and barrier properties of the composite film. Simultaneously, the porous structure provided respiratory pathways that effectively regulated the respiration intensity of preserved blueberries. Notably, the CTZ100 film (100 mg ZIF-8, 20 mg tannin) exhibited optimal overall performance, successfully inhibiting microbial spoilage, weight loss, hardness reduction, and moisture migration during storage. This approach offered valuable insights for developing biodegradable active packaging with antioxidant capabilities and enhanced respiratory support, addressing quality and safety challenges in fruit preservation.