DEVELOPMENT AND APPLICATION OF PH-INDICATOR FILMS BASED ON FREEZE-DRIED PURPLE-FLASHED SWEET POTATO, STARCH, AND CMC
freshness indicator, anthocyanins, food spoilage
Smart packaging is an emergent solution commonly used to indicate the currently quality and freshness of the food. In this study, we developed a pH indicator film by casting method, based on purple-fleshed sweet potato powder (SPP) prepared by freeze drying process, immobilized in starch or starch and carboxymethyl cellulose (CMC). The freezedrying process showed a good yield and resulted in a stable powder. The color of the powder and the films changed from pink to green with the pH change from 1 to 11. The effectiveness of the indicator films was assessed by the ground beef spoilage trial, which resulted in a color change from purple to green when the pH of the meat raised from 5.54 to 7.92. The microbiological growth and the sensory changes of the meat confirmed the deterioration process. Therefore, the developed indicator films could successfully indicate the spoilage of packaged meat products.