Polysaccharide network protection strategy enhances photodynamic stability: Unlocking new applications of edible pigments in fruit preservation

Edible antibacterial packaging films, due to their excellent biosafety and environmental friendliness, exhibit significant application potential in food preservation. However, current edible antibacterial films primarily rely on natural bacteriostatic compounds, which are limited by high dosage requirements, inconsistent performance, and narrow antibacterial spectra, making it challenging to effectively control microbial contamination. To address these challenges, we introduced erythrosine B (ERY), an FDA-approved pigment with strong photodynamic inactivation performance, combined with gellan gum (GG) to develop a novel edible photodynamic antibacterial film. Under light irradiation, ERY can rapidly generate reactive oxygen species (ROS) at a concentration as low as 5 μg/mL, thereby killing 100 % of bacteria and significantly inhibiting fungal growth. Notably, the gel network of GG serves a dual purpose by restricting ERY molecular movement and creating a protective barrier, effectively mitigating photodegradation of ERY caused by excessive ROS, thus enhancing the photostability of ERY. Experimental results demonstrate that, under identical light intensity, GG-ERY (GGE) exhibits negligible photobleaching after 30 min, showing an 8.26-fold improvement in inhibition efficacy compared to ERY, facilitating the sustained production of ROS. Owing to its efficient and long-lasting antibacterial performance, the GGE film extends the postharvest storage period of grapes to 14 days, representing a 1.75-fold increase compared to the control group. This study not only significantly enhances the antibacterial efficacy of edible films but also provides novel insights into the application of edible pigments in photodynamic antibacterial and food preservation.