Fabrication and characterization of pH-responsive intelligent films based on carboxymethyl cellulose and gelatin/curcumin/chitosan hybrid microcapsules for pork quality monitoring

The need for intelligent packaging to detect food spoilage is increasing. In this study, gelatin (GEL) and chitosan (CS) were used as wall materials for the protection of curcumin (CUR) to prepare GEL/CUR/CS microcapsules. Sodium carboxymethyl cellulose (CMC)-based films containing GEL/CUR/CS microcapsules were developed to monitor the freshness of food. A maximum CUR content of 4% can be well dispersed in the CMC matrix. The microcapsules not only improve the thermal stability of the film but also significantly improve its barrier and tensile strength. The film sufficiently controls CUR release, which is conducive to sustainable pH-change sensing. The CMC/GEL-CUR-CS film exhibits distinct color changes in different pH ranges. To test its ability as a colorimetric indicator film, we linked the changes in pork quality with the R, G, and B values of the film, and the results demonstrate sufficient accuracy. Thus, the films can be successfully applied to the deterioration monitoring of pork during storage.