Preparation of Red Cabbage-Based Intelligent/Active Composite Films Loaded with Clove Essential Oil and Their Application in Fish Freshness Monitoring.

In this study, red cabbage-based intelligent/active composite films loaded with different concentrations of clove essential oil were prepared using red cabbage slurry as the matrix, polyvinyl alcohol as the binder, glycerol as the plasticizer, and Tween 80 as the emulsifier via the casting method. The physicochemical properties, color response behavior, and antioxidant and antibacterial activities of the films were systematically evaluated and their application in fish freshness monitoring was further investigated. The results showed that the incorporation of clove essential oil significantly enhanced the antioxidant and antibacterial properties of the films and optimized their mechanical properties within a certain concentration range. Although high concentrations slightly reduced the pH response sensitivity of the films, all composite films exhibited significant color-changing ability, achieving a visible transition from red to yellow-green within the pH range of 2-12. In fish preservation experiments, the composite films not only reflected the freshness status of fish in real time through color changes but also effectively inhibited the increase in total volatile basic nitrogen, total bacterial count, and pH value, thereby delaying spoilage. In this study, a green packaging material with an intelligent indicating function was successfully developed, providing a novel solution for the quality monitoring of high-value aquatic products.