Mechanical properties of solution casted native and enzyme modified Soy protein films

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Solution casting is a low cost method to prepare films when compared to compression molding method. Soy protein concentrate (SPC) and soy protein isolate (SPI) have been used to prepare the films by solution casting method. Different polyols such as glycerol (G), trimethylol propane (T), polyethylene glycol (P) of different molecular weights, and enzymes of different specificity have been incorporated in soy protein to prepare the films. Tensile strength and elongation of all the prepared films were determined. TSPC films could not be prepared while TSPI films of good mechanical property can be prepared. Mechanical properties of the solution casted sample i.e GSPI-50, containing 50 % glycerol was same as that of GSPI-50 prepared by compression molding method. However, elongation and water uptake of the solution casted films were higher than that of compression molded films. Thermal stability of either solution casted/compression molded films showed no noticeable differences except in GSPI-50 (S), which showed third endothermic transition. Biodegradability of the films in the contaminated environment was also studied.

Soy protein, Plasticizer; Solution casted; Tensile strength