Injection Molding of Soy Protein High Moisture Extrusion with Twin Screw Extruder (Part II)

Abstract

An injection mold (250mm×50mmφ)was designed for a twin screw extruder and examined at O, 50, 150°C for wet defatted soy flour (WDSF) to make a meat analogue and liberate its shape and size from restriction of die used to conventional extrusion cooking. WDSF showed the thermoplastic property and could be texturized to the same shape and size as the mold. Microscopic analysis revealed that the product had a well alligned fibrous fine structure in its outer layer and poor or no fibrous protein metrix in its inside. When the mold temperature was changed to 150°C, no fibrous structure was observed both of outside and inside of the product. SDS-electrophoresis showed that the soluble protein fractions of outer layer and inside of the product were not so much different in all examined mold temperature. The results suggest; (1) The fibrous protein matrix is produced by the increasing shearing effect between the inner-wall of mold and the material when hot WDSF lava is extruded into the cooled mold. (2) The cooling die for wet protein extrution will have an upper limit of its opening mouth size. (3) The injection molding is one of promising method to make a large lump of meat analogue from WDSF regardless of its fine structure.