# Preparation of Chitosan-Based Emodin Antimicrobial Functional Films and Application in the Preservation of Chilled Pork

## TL;DR

This paper introduces a new antimicrobial packaging film made from chitosan and emodin that helps preserve chilled pork for longer by inhibiting bacterial growth.

## Contribution

The study introduces a novel photodynamic antimicrobial packaging material combining chitosan and emodin for food preservation.

## Key findings

- Em-Cs composite films showed excellent transparency, mechanical strength, and water barrier properties.
- Under blue light irradiation, the films generated reactive oxygen species that effectively killed bacteria.
- The film inhibited bacterial growth in chilled pork for 10 days, slowing spoilage indicators like pH increase and lipid oxidation.

## Abstract

This study aimed to develop natural, safe, and effective antimicrobial packaging materials for extending the shelf life of chilled pork during refrigeration. Emodin-chitosan (Em-Cs) composite films with varied concentrations were developed by combining the casting method with photodynamic inactivation technology, utilizing chitosan as the matrix and emodin as the functional photosensitizer for active packaging. The optical, mechanical, and barrier properties of the composite films were examined. The inhibitory effects of the samples on Escherichia coli, Salmonella Derby, Staphylococcus aureus, and Pseudomonas fragi under 450 nm blue light irradiation were evaluated. The results demonstrated that the Em-Cs composite film exhibited excellent transparency, mechanical strength, and water barrier properties, with good compatibility between emodin and chitosan. Under light irradiation, the composite film generates reactive oxygen species (ROS), whose bactericidal efficacy depends on the concentration of emodin and the duration of light exposure. When applied to chilled pork packaging, this composite film inhibited bacterial growth within the meat for 10 days, effectively retarding pH increase, lipid oxidation, and volatile basic nitrogen accumulation. The present study proposes a novel methodology for the application of photodynamic technology in the context of food preservation, and it presents a new type of natural antimicrobial packaging material for the preservation of chilled pork.