Screw configuration effects on macroscopic characteristics of extrudates produced by twin-screw extrusion of rice flour

The effects of 29 screw configurations on rice flour extrudates were investigated, The moisture content, screw speed and feed flow rate during all extrusion experiments were 15%, 400 rpm, and 12kg/h, respectively, Temperature profile in the 8 barrel sections from feed to die end were set at 0, 30, 30, 30, 70, 100, 150, and 150 degrees C, Incorporation of kneading block(KB) and reverse screw element (RSE) in screw profiles significantly influenced apparent density, product expansion (radial, axial and overall), and breaking strength, Apparent density and overall expansion were functions of die temperature, KB was the best element for maximizing radial expansion, Product hardness (breaking strength) decreased with increasing radial expansion.