System Parameters and Product Properties Responses During Extrusion of Fura from Millet-Soybean Mixtures

ABSTRACTA three-factor, three-level central composite rotatable composite design (CCRD) was adopted to study the effect of feed composition (X1), feed moisture content (X2) and screw speed (X3) on the system parameters (torque, pressure, and specific mechanical energy) and fura extrudate properties (expansion ratio and bulk density) from blends of pearl millet and soybean flour mixtures. The torque was influenced negatively but significantly (p < 0.05) by linear effects of feed composition and screw speed. The die pressure was also influenced negatively by the linear effects of the screw speed significantly (p < 0.05). The response surface plot showed that the specific mechanical energy SME was decreasing as screw speed increased while SME marginally decreased as feed moisture increased. The linear effects of the independent variables significantly (p < 0.05) affected the expansion ratio. The linear and quadratic effects of the independent variables significantly (p < 0.05) affected the bulk density. The CCRD was effective in explaining the effect of the process conditions on fura as influenced by feed composition, feed moisture and screw speed. The importance of process variables on system parameters and physical properties could be ranked in the following order: Feed Composition (X1) > Feed Moisture (X2) > Screw Speed (X3). Response variables predicted with model equations under optimum conditions were in general agreement with experimental data. The data obtained from the study could be used for control of product characteristics and possible projection for the commercial production of fura.