An intelligent colorimetric film was developed for the quality detection of tilapia fillets using bacterial cellulose (BC) as a substrate in combination with pelargonidin (Pg), cyanidin (Cy), and delphinium (Dp). The color of the BC-Pg-Cy-Dp film and Pg-Cy-Dp solution changed from rosy to blue-violet at pH 3-10. The mechanical and antioxidant properties of the film were improved after the addition of Pg-Cy-Dp. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) showed that a new hydrogen bond might be formed between the cellulose chain and the anthocyanin molecule, which increased the density of the film. The BC-Pg-Cy-Dp film displayed a large color difference from rosy to blue-violet when applied to tilapia fillet storage. The changes of K values indicated a good linear relationship with the change in ∆E at 4 °C and 25 °C. In the actual cold chain, the color of the film changed from rosy to purple, which could be identified by the naked eye and indicated that the fish were in the first fresh stage. Thus, the BC-Pg-Cy-Dp film can be used as an intelligent packaging film during storage to monitor the freshness of fish by the naked eye.
Keywords: Cold chain transportation; Fish freshness; Intelligent packaging films.
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