Intelligent multi-colorimetric cellulose acetate/cobalt-based metal-organic framework antibacterial film and its application to pork preservation

Nowadays, it is of high desirable to develop active smart films for food freshness monitoring in real time and protection. Herein, cellulose acetate (CA) matrix was incorporated with cobalt-based metal-organic framework (Co-MOF) to develop an active multi-colorimetric CA/Co-MOF film. The Co-MOF was of cubic structure, which was hydrogen-bonded with CA matrix with good dispersion. In addition to the outstanding UV-blocking capacity, the presence of Co-MOF enhanced the film′s strength, thermal stability, and barrier. Interestingly, the films of CA/Co-MOF were sensitive to ethanol (EtOH), NH₃ and NH₃-H₂S with visual color changes. Among them, the color changes towards EtOH and NH₃ were reversible, while towards NH₃-H₂S was irreversible. Furthermore, the films had good antibacterial activity. In practical application scenarios, the target film of CA/Co-MOF20 can monitor the pork freshness and extend its shelf-life by ∼100 % at 25 ℃, suggesting its good perspective in freshness monitoring and protection. This study will provide a new strategy for development of active multi-colorimetric film for food packaging.