UiO-66(Zr) MOF enhances pH sensitivity of carboxymethyl fiber colorimetric films incorporated with anthocyanins for monitoring fish freshness.

The non-destructive, real-time, and visual assessment of fish freshness is crucial for maintaining food quality and safeguarding public health. In this study, a pH-sensitive and colorimetric enhancement film was developed using a carboxymethyl cellulose/anthocyanin/metal-organic framework (CMC-BA-UIO). The concentration of UIO-66 in the film-forming solution significantly influences the mechanical properties and ammonia responsiveness of the indicator film, with the CMC-BA/2.5%UIO-66 variant exhibiting optimal performance. When utilized for real-time fish freshness monitoring at 4 °C, the CMC-BA/2.5%UIO-66 indicator film demonstrated a distinct color transition from purple to yellow, which exhibited a strong correlation with the rot index (TVB-N) of the fish. These findings indicate that the developed indicator film has potential applications in intelligent packaging for monitoring food shelf life, providing a visual alert to producers and consumers regarding food spoilage.