Optimization of processing parameters on the proximate properties of maize and soybean extrudates

Maize (TZSR-W-1 NARZO-20) and soybean (TGX1448) flours were used for the development of extruded products. The flour formulations were maize (46-52%), soybean (21-32%), and moisture content (16-26%). Central Composite Design (CCD) in Response Surface Methodology consisting five factors (maize to soybean-water weight ratio -X1, soybean to water weight ratio -X2, barrel temperature (120, 160 and 200oC) -X3, die diameter (6, 8 and 10mm) -X4 and screw speed (120, 160 and 200rpm) -X5 at three levels was used to determine the optimum process condition for the proximate properties of the extruded products. The process parameters significantly influenced the dependent variables at p<0.05. The coefficients of regression (R2) for the response equations ranged between 0.967 and 0.999 which is an indication that the variables were adequately fitted to the regression equation and could predict the proximate values of the extrudates. The optimum process condition at desirability index of 1 were X1 (0.99), X2 (1.10), X3 (190oC), X4 (124rpm) and X5 (10mm).