Natural anti-photooxidative packaging via UV-shielding and activity dual enhancement of vanillin non-covalently modified carboxymethyl cellulose film.

In this study, an anti-photooxidative green food packaging material based on carboxymethyl cellulose (CMC) and vanillin (VA) was successfully fabricated, with simultaneous antibacterial and antioxidant properties. The ultraviolet-shielding (UV-shielding) performance of the composite films was systematically evaluated at pH 5.0, 7.0, 8.5, and 11.5, revealing that alkaline conditions markedly enhanced UV-shielding capacity of the films. In comparison with the control group, the incorporation of VA significantly reduced the UV transmittance of the composite films while maintaining excellent transparency. Specifically, the modified film achieved 100% UV-shielding efficacy for UVC and UVB, and 99.7% for UVA, while maintaining a transparency of over 80%. They demonstrated significant antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Additionally, the films exhibited robust antioxidant capacity, with 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS+) radical scavenging ratios of 55.34-99.10% and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ratios of 14.69-44.60%. Practical validation experiments revealed that the composite films effectively mitigated UV-induced degradation of photosensitive nutrients (anthocyanins and vitamin C) and extended the shelf life of strawberries to 7 days at 25 °C (vs. 3-4 days for unpacked group), while retaining 30% more vitamin C. In summary, this study offers a green, cost-effective and sustainable approach to preparing high-performance UV-shielding food packaging films.