pH-responsive chitosan-based film containing oregano essential oil and black rice bran anthocyanin for preserving pork and monitoring freshness.

This study developed an intelligent and antibacterial packaging film using a chitosan matrix embedding oregano essential oil (OEO) and black rice bran anthocyanin (BRBA). Herein, OEO and BRBA were immobilized into the chitosan matrix through noncovalent bonds and uniformly distributed in the films. The chitosan-OEO-BRBAⅡ film exhibited excellent mechanical, antibacterial, antioxidant, and UV-vis light barrier properties, and sensitive and rapid response to pH/NH3. Furthermore, fresh pork was coated with the film for monitoring the freshness and preservation efficiency at 4 °C for 12 days. The film effectively improved the quality indices of pork, including the sensory index, total viable counts, pH, TVB-N value, and color of pork during the storage at 4 °C. The film reduced the abundance of spoilage bacteria related to stress tolerance, pathogenicity, and biofilm formation in the pork. Their odorous volatiles appeared later and were less than those in the untreated group.