Natural pH indicator from tapioca starch/curcumin film

Abstract

An intelligent packaging film based on natural product was prepared from tapioca starch and curcumin. Curcumin was extracted from turmeric using a Soxhlet extractor. The visual color changes of curcumin solution were investigated at different pH values (pH 5-11). It can be seen that the color changes of curcumin solution changed from yellow to reddish-brown as the pH values changed from 7 to 8. Additionally, curcumin was added into the tapioca starch and prepared as a bio-film by a solution casting technique. The visual color changes and color parameters (CIELab color system) of tapioca starch/curcumin film at different pH values (pH 5-11) were observed. The color of tapioca starch/curcumin film changed from yellow to dark orange color as the pH values increased. Moreover, the addition curcumin to the tapioca starch film can increase contact angle and elongation at break. As a result of a change in film colors, the tapioca starch/curcumin film could be applied as a natural pH indicator for monitoring food spoilage based on the pH changes. Moreover, an environmentally friendly indicator film was also achieved.