An edible, photodynamic antimicrobial and fluorescent film containing aggregation-induced emission luminogens from berberine and citric acid for freshening cooked chicken

Some chemicals used as preservatives may be found to be harmful to human health as a result of clinical studies conducted over time, or their limits may be updated. Natural, safe and antibacterial food packaging can simultaneously maintain the food quality, reduce preservative usage and prevent foodborne diseases. In this work, an edible, green and fluorescent packaging film with photodynamic inhibition of Staphylococcus aureus and Escherichia coli was prepared through incorporating the salt of berberine and citric acid (CA) into a composite film of carboxylated cellulose nanofibrils (CCNF) and κ-carrageenan (κC). The berberine/citric acid salt (BCA) was successfully synthesized via simple metathesis reaction, which endowed the blended film with improved thermal stability, ultraviolet shielding, water vapor barrier and mechanical properties. Among the prepared films, the film prepared from 0.6 g of CCNF and 8% of BCA (κC-CCNF-BCA8) showed the strongest fluorescence, the highest ROS production capacity and antimicrobial rate of 100% against both E. coli and S. aureus under white light. The total number of bacterial colonies in cooked chicken packaged in κC-CCNF-BCA8 film was 2.36 Log CFU/mL, which was lower than that packaged in κC-CCNF film (3.00 Log CFU/mL). The sustainable and fluorescent film could kill microorganisms in cooked chicken with only adequate sunlight and has a promising application in antibacterial packaging.