An Antioxidant and Intelligent pH-Sensitive Composite Film Based on Gelatin and Persian Gum Using Purple Carrot Extract

Abstract

The present research is aimed at developing novel intelligent pH-sensitive films based on Persian gum and gelatin using purple carrot extract. To this end, films were developed by mixing polymer solutions containing Persian gum (5%) and gelatin (5%), in equal proportions and partially replacing distilled water of solutions with purple carrot extract at 0, 15, 30, and 45%. Total anthocyanin content, antioxidant activity, color indices, and tensile strength of films were evaluated. Purple carrot extract incorporation in the film caused a slight reduction in the lightness and an increase in the anthocyanin content, DPPH inhibition, yellowness, redness, and tensile strength. The sample containing 45% extract (anthocyanin concentration was 2.39 mg/ml) was selected as the best pH-sensitive film based on mechanical and antioxidant properties and evaluated in terms of moisture content, moisture absorption, pH, heat seal ability, thickness, contact angle, FTIR, X-ray diffraction, and colorimetric tests. The sensitivity of the film to pH changes was assessed in the range of 2-12. The color of the film changed from pink to blue as a function of pH. The results proved that films based on Persian gum, gelatin, and purple carrot extract could be used as novel food grade biomaterials to monitor the freshness/spoilage of food.