Preparation and characterization of purple sweet potato starch-based edible film with optimized mixing temperature

Abstract

In recent years the various types of edible starch films have been gaining commercial value. Purple sweet potato (PSP) contains more than 15 % starches in its root and displayed good potential to become the main raw material in producing edible film due to its functional antioxidant properties. By adding glycerol as plasticizer and kappa carrageenan as gelling agent to the starch helped strengthened and improved the formulation of the edible film. Film properties were found to be dependent on the mixing temperature processing conditions. Attributes like low water vapour permeability (WVP) of the film were obtained with a lower mixing temperature condition while the highest antioxidant capacity (75.84 %) was exhibited at 70 °C mixing temperature. In addition, scanning electron microscopy revealed the highest temperature (80 °C) used in the mixing process resulted in a film with smaller porosity compared to that produced with the lowest temperature (50 °C). Nevertheless, the optimum behaviour of PSP film was obtained by using defined formulations at mixing temperature of 70 °C to obtain high antioxidant capacity and low WVP (0.0214%).