Preparation and Characterization of Pullulan-Soy Protein Concentrate Biocomposite Film

The non-biodegradable nature of plastic packaging has brought about an attention in bio-basedpackaging materials. Edible composite films were prepared using soy protein concentrate (SPC) and pullulan(PUL) biopolymer at five different ratio (100:0; 70:30; 50:50; 30:70 and 0:100) with glycerol as plasticizer bycasting-evaporation method. The thickness, mechanical properties, water vapor permeability (WVP), solubilityand color of the film specimens were investigated. Increasing PUL content decreased the thickness, and tensilestrength but the visual properties, elongation at break, WVP, and solubility in water of the films improved,simultaneously. In addition, the crystalline properties and microstructure of the bio-composites werecharacterized by X-ray diffraction and Scanning Electron Microscopy (SEM), respectively. Homogenousmicrostructure and crystalline properties of the films showed good affinity with mechanical and functionalproperties of the films. The optimum mechanical properties and WVP were obtained at the SPC to PUL ratio of50:50. These findings support the potential of the equal proportion of SPC/PUL biocomposite as a foodpackaging material.