Chitosan/PVA composite film enhanced by ZnO/lignin with high-strength and antibacterial properties for food packaging.

This study aims to develop a chitosan/polyvinyl alcohol (CS/PVA) composite film (QZCS/PVA) for food packaging, enhanced by the incorporation of quaternary ammonium lignin/ZnO nanoparticles (QAL/ZnO) to improve its antibacterial, antioxidant, and mechanical properties. The QAL/ZnO nanoparticles were synthesized using a co-precipitation method, resulting in a synergistic effect that enhances the uniformity and stability of the composite film. The double cross-linked CS/PVA composite film containing QAL/ZnO nanoparticles effectively mitigates the brittleness of pure chitosan films, achieving a tensile strength of 95.89 MPa. Crucially, the inclusion of QAL/ZnO imparts exceptional antioxidant and antibacterial properties to the QZCS/PVA composite film. Disk diffusion assays revealed markedly enhanced antibacterial efficacy against Staphylococcus aureus and Escherichia coli in comparison to analogous biopolymer films. The dense network structure of the composite film also provides excellent water resistance, which contributes to extending the shelf life of food products. In a 12-day grape preservation experiment, the composite film exhibited outstanding preservation performance. These results underscore the potential of the CS/PVA composite film containing lignin and chitosan for food packaging applications, offering significant advantages in improving food preservation.