Improving the Performance of Chitosan Films Using ZnO Nanoparticles as Food Packaging

Chitosan–ZnO nanocomposite films were developed as robust, multifunctional, and eco-friendly active food-packaging materials. Chitosan is biodegradable, biocompatible, non-toxic, and antimicrobial, but its pure films are brittle, weak, and highly permeable to gases and moisture. To overcome these drawbacks, ZnO nanoparticles were synthesized by chemical precipitation and uniformly dispersed into chitosan solution. The resulting films were transparent, flexible, and showed homogeneous nanoparticle distribution. Mechanical tests demonstrated enhanced tensile strength and flexibility, while oxygen and water vapor permeability significantly decreased. Antibacterial assays confirmed strong broad-spectrum activity against both Gram-positive and Gram-negative bacteria. Optical studies revealed excellent UV-blocking ability, protecting food components from photodegradation. Structural and thermal analyses (SEM, XRD, FTIR, TGA) verified strong interfacial compatibility and improved thermal stability. Biodegradation experiments showed that ZnO did not hinder natural chitosan breakdown, ensuring environmental safety. Overall, these nanocomposite films successfully integrate mechanical reinforcement, barrier improvement, antimicrobial and UV-protective functions, and full biodegradability. They offer a sustainable and technologically promising alternative to conventional petroleum-based food packaging.