Microstructure and mechanical properties of soy protein/agar blend films: Effect of composition and processing methods Original Research Article

The present work prepared a series of soy protein isolate/agar blend films containing 33% glycerol as plasticizer by solution casting and thermo-molding methods. The microstructure and mechanical properties of the blend films were evaluated in relation to the agar/protein ratio as well as the processing methods. Experimental results revealed that hydrogen bonding interactions existed between soy protein and agar. The casting films possessed more homogeneous interfaces compared with the molding films, leading to the superior mechanical properties than those molding films. Owing to the rigid three-dimensional network formed by the agar, the tensile strength of casting blend films was enhanced. With the increase of agar in the casting blend films, the crosslinking density increased and was responsible for the variations in tensile strength.