Preparation of pectin/carboxymethyl cellulose composite films via high-pressure processing and enhancement of antimicrobial packaging

This study investigated the impact of high-pressure processing (HPP) treatment on the structure and physicochemical properties of pectin (PEC)/carboxymethyl cellulose (CMC) composite films, along with the development of new active films incorporating emodin as an antibacterial agent. The results showed that 500 MPa/20 min HPP treatment significantly improved the tensile strength (from 45.91 ± 4.63 MPa to 52.24 ± 4.87 MPa) and elongation at the break (from 5.00 ± 1.44 % to 11.72 ± 2.97 %) of the films. It also improved the film's thermal stability and had no significant effect on its thermal degradability. Moreover, emodin was incorporated into the PEC/CMC film-forming solution and subjected to 500 MPa/20 min HPP treatment to investigate the structure, functional properties, optical properties, and antibacterial activity of the film. The emodin caused the film structural alteration, but significantly improved the water vapor barrier properties. It also reduced the film brightness and light transmission. The antibacterial assessment demonstrated that the film's antibacterial activity was correlated positively with increasing emodin content, and the number of viable cells of Staphylococcus aureus decreased by 1.29 log 10 CFU/mL, 1.70 log 10 CFU/mL, and 1.80 log 10 CFU/mL with different levels of EM antimicrobial films after 12 h.