Effect of various polyols and polyol contents on physical and mechanical properties of potato starch-based films

The present study investigated effects of plasticizer (glycerol, xylitol and sorbitol) and relative humidity on physical and mechanical properties of potato starch-based edible films. Films were obtained from solutions containing gelatinized starch, polyol and water by casting and evaporating water at 35 degrees C. Water content of films increased with increasing relative humidity and plasticizer content. Water vapor permeability of films increased with increasing plasticizer content and storage relative humidity. Young's modulus decreased with increasing polyol content with a concurrent increase in elasticity of films. Both increased polyol and water content increased elongation at break with a decreased tensile strength. Glass transition temperatures decreased as a result of plasticization as polyol and/or water content increased. Effects of plasticizers on physical and mechanical properties of films were largest for glycerol and smallest for sorbitol. High contents of xylitol and sorbitol resulted in changes in physical and mechanical properties of films probably due to phase separation and crystallization. (c) 2006 Elsevier Ltd. All rights reserved.