A novel dual-signal response Zn-MOF intelligent active label prepared from polyvinyl alcohol/starch for real-time visual monitoring shrimp freshness.

With the increasing concern over food safety, the development of smart labels capable of visually monitoring food freshness in real-time has become increasingly urgent. In this study, a novel zinc-based metal-organic framework (Zn-MOF) was synthesized and incorporated into a poly(vinyl alcohol) and starch matrix to prepare PS@Zn-MOF composite films. The films demonstrated colorimetric and fluorescent dual-signal responsiveness, ammonia sensitivity, and antimicrobial properties. A comprehensive evaluation of the films revealed excellent mechanical properties, UV shielding ability, and water vapor barrier capabilities. Furthermore, the films exhibited color stability, with a ΔE value change of <2.4 after 40 days of exposure. When applied to monitor shrimp spoilage, the films shifted from yellow-brown to purple-red in daylight and from blue to violet fluorescence under UV light. The color difference and fluorescence intensity in both response modes were linearly correlated with TVB-N values. The shrimp packaging application demonstrated that the films effectively maintained shrimp freshness. These findings suggest that the dual-signal intelligent freshness monitoring system based on PS@Zn-MOF composite films presents a promising solution to food safety challenges.