Effect of type and content of binary polyol mixtures on physical and mechanical properties of starch-based edible films

The present study investigated effects of binary mixtures (1:1) of glycerol, xylitol and sorbitol at various concentrations on physical and mechanical properties of potato starch-based edible films stored at various relative vapor pressures (RVP). Edible films were prepared by casting using suspension of binary polyol mixtures (20–50% of solids), potato starch (50–80% of solids) and distilled water which was heated to gelatinize starch. Water sorption of films was affected by the type and content of binary polyol mixture. Water vapor permeability (WVP) of films was found to increase as the content and plasticization effect of binary polyol mixture as well as RVP gradient increased. Young’s modulus of films was observed to decrease with the concurrent increase of elongation at break as the plasticization and the content of binary polyol mixture increased at RVP of 33%. Both tensile strength and elongation at break decreased when films were plasticized at the high content of binary polyol mixtures and stored at the RVP of 54% and 76%. Crystallization of polyols was not observed when binary polyol mixtures were used as plasticizers.