Physicochemical properties and solubility of sweet potato starch-based edible films

This study aimed to develop a sweet potato starch (SPS)-based edible film with improved water solubility. Initially, types of sweet potatoes were used, and their characteristics were analyzed to select the most appropriate variety for edible films. Shingeonmi was finally selected, and a chemical modification of starch, acetylation with different concentrations of acetic anhydride (1, 5, and 9 mL), was conducted to improve the water solubility. During the film-forming process, amidated pectin (AP) and calcium chloride (CaCl₂) were also compounded to enhance the solubility. The developed native and acetylated SPS films, with or without the two substances, were further used to investigate various physicochemical properties and water solubility. Acetylated SPS-based films with AP and CaCl₂ showed excellent water solubility (99.16%) than the native SPS one, indicating the beneficial effect of variables (acetylation, AP, and CaCl₂) for enhanced water solubility. These results imply the potential use of the developed water-soluble film to package food ingredients and products such as vegetables, bakery, meat, or seafood due to the enhanced solubility and edibility.