An intelligent thymol/alizarin-loaded polycaprolactone/gelatin/zein nanofibrous film with pH-responsive and antibacterial properties for shrimp freshness monitoring and preservation.

Improper storage methods cause food resources to be wasted, and the development of multifunctional intelligent packaging can realize freshness monitoring and extend the shelf life. In this study, an intelligent alizarin/thymol-loaded polycaprolactone/gelatin/zein nanofibrous film was prepared and achieved the dual functions of pH-responsive and antibacterial properties. The film was fabricated using electrospun technology and characterized by SEM, FT-IR, WCA, TGA, DSC, and mechanical property tests, which had good antioxidant properties (81.40 ± 0.74 % free radical scavenging). The film could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus, and Shewanella putrefaciens within 12 h and exhibited light yellow-light purple-dark purple color change at pH 2-12, with good color stability and color responsiveness to ammonia in the environment. In the shrimp application, shelf life was extended by 2 days and freshness could be monitored by the color change. This scientific research opens up new possibilities for realizing multifunctional food packaging alternatives.