Poly(vinyl alcohol)/zwitterionic chitosan composite film with UV-blocking, antibacterial, and antioxidant properties: structural design, performance optimization, and food preservation application

A novel zwitterionic chitosan derivative (5OHSCS) was synthesized via EDC/NHS-mediated coupling and incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate PVA/5OHSCS composite films by solution casting. This work aimed to develop an active packaging film for food preservation with integrated antibacterial, antioxidant, and UV-blocking functions. The chemical structure, physicochemical properties, and functional performance of the films were systematically characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), as well as optical measurements, mechanical testing, water vapor permeability (WVP), and water contact angle analysis. Compared with neat PVA film, the PVA/5OHSCS composite films showed improved functional properties. Under the optimized formulation, the antibacterial inhibition rates reached 95% against Escherichia coli and 100% against Staphylococcus aureus , together with enhanced in vitro radical-scavenging activity. In addition, the composite film exhibited reduced UV-region transmittance, suggesting a certain UV-shielding capability. Cytocompatibility evaluation showed that 293 T cell viability remained above 80%, indicating no obvious cytotoxicity under the tested conditions. A strawberry storage study at room temperature further suggested that the composite film could help delay quality deterioration, improve weight-loss control and texture retention, and prolong the shelf life of strawberries to some extent within the tested storage period. Overall, the PVA/5OHSCS composite film may provide a feasible strategy for the design of multifunctional PVA-based active packaging materials with potential in fresh produce preservation.