Arginine-modified chitosan-based photodynamic food packaging film for effective preservation of cherry tomatoes

Photodynamic inactivation holds promise for food packaging, yet its application is hindered by poor efficiency against Gram-negative bacteria. This study developed an active composite film based on food-grade, positively-charged chitosan (CS) and a hierarchically structured composite (HPZA). Under visible light illumination, HPZA generated substantial reactive oxygen species, causing bacterial membrane disruption and subsequent ion leakage. As a result, HPZA at 60 μg/mL achieved a 5 log 10 reduction in Escherichia coli , and at 80 μg/mL it reduced Staphylococcus aureus from 6 log 10 to 1 log 10  CFU/mL. Furthermore, it exhibited potent light-driven antifungal activity against Botrytis cinerea . With HPZA as a functional active filler, the CS-based films exhibited enhanced physicochemical performance, including a 53.48% increase in elongation at break, a 24.27% increase in water contact angle, and increased visible light absorbance. In a practical application, the CS-HPZA 2.00% film effectively extended the shelf life of cherry tomatoes from 2 to 10 days, while maintaining fruit firmness and total soluble sugar content, with minimal difference from the fresh group. These findings highlight CS-HPZA as a promising light-driven antimicrobial packaging film for active food packaging applications.