A light-driven photodynamic antimicrobial and UV-barrier chitosan film doped with well-dispersed aloe emodin through electrostatic interactions for pork preservation.

Aloe emodin (AE) molecules tend to aggregate in aqueous film-forming solutions, which is not conducive to develop photodynamic antimicrobial films. In this work, the water-soluble chitosan quaternary ammonium salt (CQAS) was used to improve the dispersion of AE in chitosan film through electrostatic interaction to achieve a photodynamic antibacterial effect. The optimal tensile strength and elongation at break of the film reached 27.36 MPa and 76.40%, respectively. With rising AE content, the film exhibited enhanced UV-shielding performance. The film with 0.7% AE (CS-C-AE0.7 film) possessed the highest reactive oxygen species (ROS) production capacity, exhibiting photodynamic sterilization against Staphylococcus aureus, Escherichia coli, Penicillium citrinum and Aspergillus Niger under light irradiation, with inhibition ratios of 99.24%, 94.61%, 100% and 87.45%, respectively. After 6 days, the pork packaged by CS-C-AE0.7 film had the lowest total viable count of 5.15 log CFU/mL in the condition of light irradiation.