Influence of extrusion conditions on system responses during twin screw extrusion of barnyard millet based extrudate

摘要

Extrusion cooking process proved to be very versatile and energy efficient process. In the present study, the blend of 75% barnyard millet, 23% defatted soy flour and 2% moringa leaf powder was extruded through co-rotating twin-screw extruder. A three factor, three levels Box-Behnken design of response surface methodology (RSM) was applied to investigate the effect of screw speed (300-400 rpm), barrel temperature (110-120(0)C) and feed moisture content (15-21%) on the system responses. System responses were product temperature (PT), motor torque (MT) and specific mechanical energy (SME). Based on the system parameters and regression analysis, regression equations were developed for evaluating the impact of an extrusion processing conditions on selected system responses. All three independent variables affected the process responses significantly. As the screw speed increased, barrel temperature and specific mechanical energy increased, whereas motor torque decreased. Reduction in the feed moisture content resulted in significant (P&0.05) increase in PT, SME, and MT. Increase in the level of barrel temperature resulted in significant (P&0.05) decrease in both SME and MT, whereas the significant (P&0.05) increase in product temperature.