Soluble soybean polysaccharide: A new carbohydrate to make a biodegradable film for sustainable green packaging

Biodegradable edible films based on soluble soybean polysaccharide (SSPS), a new film-forming material, and three levels of glycerol (20%, 30% and 40%, w/w) as plasticizer, were developed and evaluated in terms of physical, mechanical, barrier and optical properties as well as their microstructure. SSPS-based films with a concentration of 20% glycerol possessed the lowest water vapor permeability. Increasing the glycerol content increased (P<0.05) values for elongation at break, but decreased (P<0.05) tensile-strength values. It was found that plasticizer concentration significantly affected the films' glass-transition temperature; however, it had no significant effect on their melting point. Color measurement showed that increasing the glycerol concentration caused the b and L values to increase, while Delta E value decreased. These results were explained by the film's microstructure, which was analyzed by atomic force microscopy and scanning electron microscopy. The results indicated that SSPS could be a promising food-packaging material. (C) 2013 Elsevier Ltd. All rights reserved.