INFLUENCE OF LOCUST BEAN GUM ADDITION ON PROPERTIES OF SOY PROTEIN BASED FILMS

Abstract

Soy protein is the most important representative of legume protein and has presented high potential to manufacture films. Blends between protein and polysaccharide can to improve the performance, stability, functionality and resistance of biopolymer films in comparison to simple films. This work aims to develop composite films with soy protein isolate (SPI) and soy protein concentrate (SPC) and different locust bean gum (LBG) concentration, as well as, to evaluate the effect of polysaccharide addition on optical and mechanical properties, water vapor barrier, color, microstructure, solubility and moisture of the SPI and SPC films. For this purpose, composite films were elaborated varying LBG concentration (0; 0.05; 0.1; 0.2; 0.3; 0.4%) and fixing SPI and SPC (5%) concentration in solution. Glycerol was used in all formulations as plasticizer. Microstructure, solubility, moisture, water vapor permeability, optical and mechanical properties of the simple and composite films were evaluated. The solubility and film barrier to the light was increased in SPI films with LBG addition, but was not changed in SPC films with gum addition.All composite films presented higher tensile strength values than simple films. The lightness of composite films was smaller than simple films, however water vapor barrier was similar.