| Abstract: | Three streams of corn dry-milled products (corn grits, corn cones, and corn flour) were sieved and separated according to average diameter, and some segregated fractions were ground to produce nine streams. Corn grits were separated to produce grits with diameters of 1.19 and 0.841 mm, and selected fractions were ground into grits with average diameters of 0.297 and 0.210 mm. Corn cones were separated into average diameters of 0.595, 0.420, and 0.297 mm. Corn flour was separated into fractions with average diameters of 0.297 and 0.210 mm. The original and the additional streams were extruded at constant speed (50 rpm) and at three different processing extruder barrel temperature profiles: low (LTP, 100-110-120°C), medium (MTP, 110-120-130°C), and high (HTP, 120-130-140°C). The least significant difference (P < 0.01) test showed that additional grinding of corn grits affects the expansion ratio of extrudates processed at LTP and HTP. Additional separation of corn flour affects (P < 0.01) the bulk density and water solubility index of extrudates at HTP. At HTP, corn cones with diameters of 0.595 mm had significantly (P < 0.01) higher torque, specific mechanical energy, and die pressure than did the original corn cone extrudates without separation. |
