Films based on κ-carrageenan incorporated with curcumin for freshness monitoring

Novel films based on κ-carrageenan (Car) incorporated with curcumin (Cur) were developed for freshness monitoring of foods. Cur and Car were interacted by hydrogen bonds. A low amount of Cur (no higher than 3%) could be well-dispersed in Car matrix. These characteristics significantly improved the film barrier and tensile strength, besides the enhancement of thermal stability. Hence, the Car film with 3% Cur exhibited the best performance. The films showed a good release control of Cur and a predominant Fickian diffusion release mechanism, which was favorable to sustainable pH change sensing. The Car-Cur films demonstrated a strong redness-shift under alkaline condition. This characteristic was successfully used to monitor the spoilage of pork and shrimp during storage. As a pH colorimetric indicator, the Cur incorporated Car films may have a great potential in the freshness monitoring of foods.