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 ΔE 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.