CS-DES-OEO hot-pressed films with improved heat-sealing strength and antimicrobial activity for white bread preservation.

Chitosan (CS), a renewable natural polymer, facing constraints in its application within the food packaging field due to the low heat-sealing strength after film formation by the casting method. This study successfully developed a novel and environmentally friendly CS active composite film via hot-press method. Although oregano essential oil (OEO) slightly reduced tensile strength (TS), it improved elongation at break (EAB) (140% increase), heat-seal strength (18.5% increase), and potentiated antibacterial effects against E. coli and S. aureus compared with the CS-DES film. In the preservation of white bread, the CS-DES-OEO film effectively inhibited microbial growth, and the shelf life was extended by at least 4 days compared to conventional polyethylene (PE) packaging. This study verified the green characteristics of the choline chloride-based DES and OEO, addressed the inherent limitation of the low heat-seal strength of CS films, and further demonstrating the potential of CS-based active packaging in food preservation applications.