The fabrication of chitosan/MOF smart packaging composite film and its application for simultaneous freshness preservation and monitoring of yak meat.

Sustainable, multifunctional packaging with real-time freshness monitoring and shelf-life extension is crucial for beef quality and safety. This research investigates the incorporation of an ammonia-sensitive cobalt-based metal-organic framework (Co-MOF) into a chitosan (CS) polymer matrix to develop a functional composite film designed for extending the shelf life of yak meat. Results showed uniform Co-MOF evenly distributed in CS matrix, bonded steadily with CS via hydrogen bonds and covalent (Co-COOH).The integration of Co-MOF marked improvement in its structural strength, achieving a tensile strength of 15.3 MPa and a breaking elongation of 46.64% at 6 wt% Co-MOF. The films demonstrated outstanding barrier performance, showing water vapor transmission rate (WVTR) of 0.934 × 10-3 g·cm/cm2·KPa·h and an oxygen permeability of 6.275 cm3/m2·24h·0.1 MPa. The water contact angle was 85°, and the film showed superior ultraviolet shielding with 16.74% transmittance at 400 nm when the Co-MOF content was 8 wt%. In terms of preservation, the CS/MOF films demonstrated excellent antibacterial activity. The films monitored yak meat freshness via color change, extending its shelf life by 2 days. Additionally, the films exhibited good biodegradability, fully degrading within 78 days when buried in soil, releasing approximately 97 μg of cobalt from the CS/MOF-8 film.