preparation and characterization of pullulan-soy protein concentrate biocomposite film

The non-biodegradable nature of plastic packaging has brought about an attention in bio-based packaging materials. edible composite films were prepared using soy protein concentrate (spc) and pullulan (pul) bio-polymer at five different ratio (100:0; 70:30; 50:50; 30:70 and 0:100) with glycerol as plasticizer by casting evaporation method. the thickness, mechanical properties, water vapor permeability (wvp), solubility and color of the film specimens were investigated. increasing pul content decreased the thickness, and tensile strength 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 were characterized by x-ray diffraction and scanning electron microscopy (sem), respectively. homogenous microstructure and crystalline properties of the films showed good affinity with mechanical and functional properties of the films. the optimum mechanical properties and wvp were obtained at the spc to pul ratio of 50:50. these findings support the potential of the equal proportion of spc/pul bio-composite as a food packaging material.