Development and application of pH‐indicator film based on freeze‐dried purple‐fleshed sweet potato, starch, and CMC

Abstract

SummarySmart packaging is an emergent solution commonly used to indicate the current quality and freshness of the food. In this study, a pH indicator film without an anthocyanin‐extraction step was developed, based on purple‐fleshed sweet potato powder (SPP) prepared by freeze drying process, with starch or starch and carboxymethyl cellulose (CMC). The colour 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 colour 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, developed indicator films could successfully indicate the spoilage of packaged ground beef.