Physical properties of biodegradable films from heat-moisture-treated rice flour and rice starch

Native starch and flour are not successful in biodegradable film production. Heat moisture treatment (HMT) is a physical modification to improve functional properties of starch and flour, however, it is not fully understood if this method can enhance their film properties. This research, compares physical properties of biodegradable films produced from native rice flour (RF), rice starch (RS), and their heat-moisture-treated counterparts (HMTRF and HMTRS, respectively). Water solubility of the films reduced in the following order: RS film (23.91%) > RF film (19.77%) > HMTRS (19.50%) > HMTRF (16.22%). Water vapor permeability values of RF and RS films were 0.032 and 0.017 g mm m-2 h-1 KPa-1 which were increased to 0.043 and 0.027 g mm m-2 h-1 KPa-1, respectively, after HMT. RF film was darker, more reddish, and yellowish but less transparent than RS film. HMT increased all the color parameters and further reduced the transparency of the films particularly for RF film. RS films had less flexibility, higher elongation at break, and tensile strength than RF films. HMT reduced films firmness, tensile strength, and resistance to stretch of both films. Overall, biodegradable films from HMTRF and HMTRS showed lower transparency, water solubility, rigidity, and extensibility while higher permeability to water vapor compared to their native counterparts