Enhanced ammonia-sensitive intelligent films based on a metal-organic framework for accurate shrimp freshness monitoring

Sensitive intelligent films can be used to accurately monitor food freshness. In this study, a cellulose acetate curcumin-loaded cyclodextrin (CD)-based metal-organic framework intelligent film (CA-Cur@CD-MOF) was developed to monitor shrimp freshness at different spoilage stages in real time. The mechanical, barrier, optical, and ammonia-sensitive properties of this film were studied. Notably, this film demonstrated effective ammonia-sensitive color development, reaching a ΔE value of 8.5 in 2 min under an ammonia atmosphere of approximately 0.4 mM. This intelligent film exhibits good DPPH free radical scavenging ability, high thermal stability, and excellent theoretical limit of detection (LOD). Interestingly, shrimp can be classified as "fresh", "sub-fresh", and "spoilage" during the monitoring of shrimp freshness. Furthermore, a significant correlation (R² = 0.9641) was observed between the TVB-N and ΔE value for this film. Therefore, this intelligent film is promising for the real-time monitoring of freshness of shrimp and other protein-rich foods.