Vol. 9, Special Issue 10, Part W (2025)

The growing interest in sustainable food packaging has encouraged the development of intelligent films that can signal product freshness through visible color changes. In this study, biodegradable pH-sensitive films were prepared using biopolymers blends (sodium alginate-carboxymethyl cellulose (SA-CMC), sodium alginate-chitosan (SA-CS) and sodium alginate-pectin (SA-P) blends incorporated with anthocyanins extracted from butterfly pea flower (Clitoria ternatea L.). Ultrasound-assisted extraction (UAE) of anthocyanins from butterfly pea flower was carried out at 225 W ultrasound power, 35 minutes of sonication time, and a 1:30 g/ml of solid-solvent ratio. Glycerol was used as plasticizer for film development. Results showed that the film formed by using sodium alginate-carboxymethyl cellulose (SA-CMC) blend possess good strength and was the best among three films. It was also observed that the films having glycerol concentration of 30% (w/w, based on total polymer weight) had better flexibility and reduced brittleness. The developed SA-CMC film exhibited clear, uniform coloration and responded to pH changes by shifting from violet to green during chicken storage. Films applied to chicken samples at room and refrigeration temperatures displayed distinct color changes corresponding to spoilage progression. These biodegradable intelligent films show potential as sustainable freshness indicators for perishable food monitoring.