Light-responsive biopolymeric films embedded with natural polyphenols: ROS-mediated suppression of postharvest microbial decay in perishable fruits

The development of advanced antimicrobial packaging is crucial for ensuring food safety. This paper reports a novel photodynamic antibacterial film (PVA-CM@TFQ) that effectively combats microbial contamination, delays food spoilage and minimizes the risk of foodborne diseases transmission. Quercetin (Que) was encapsulated within a tannic acid-ferric ion (TA–Fe³⁺) coordination network and embedded into a biodegradable polymer matrix composed of polyvinyl alcohol (PVA) and carboxymethyl chitosan (CM). The TA-Fe³⁺ network significantly improved the stability of Que, while the resulting PVA-CM@TFQ demonstrated excellent mechanical properties, barrier performance, and biocompatibility. Upon light irradiation, the film produced reactive oxygen species (ROS), exhibiting potent photodynamic antibacterial activity, with inhibition rates of 99.83 %, 99.42 %, 100 %, and 100 % against Escherichia. coli, Staphylococcus. aureus, Candida. albicans, and Saccharomyces cerevisiae, respectively. When applied to raspberries, hawthorn, goldenberries, and lime, the film effectively prolonged shelf life by suppressing microbial proliferation, minimizing weight loss, and maintaining fruit firmness. These findings highlight a sustainable, light-responsive strategy for fruit preservation with significant potential in enhancing food safety.