Optimization of extrusion process variables for development of pulse-carrot pomace incorporated rice based snacks

Different experimental combinations of extrusion process variables i.e. screw speed, die temperature, moisture content and proportion of ingredients were tried using Box-Behnken design of experiments. Response surface methodology (RSM) was used to investigate the effect of screw speed (300–500 rpm), die temperature (120–180° C), moisture content (14–20%) and proportion of ingredients (rice flour: pulse flour: carrot pomace powder-60-80%: 10–30%: 10%) on protein, fiber, overall acceptability, colour and texture of extruded products. The extrusion process was optimized for maximum protein, fiber, overall acceptability and minimum hardness with colour difference within experimental range. The optimum operating conditions using selective quality parameters for screw speed, die temperature, moisture content and rice proportion in ingredient composition was 340 rpm, 120°C, 20% and 60%, respectively. An analysis of variance (ANOVA) revealed that among the process variables, sample formulation followed by screw speed had the most significant effect on all the responses; die temperature and moisture content had the significantly higher effect on overall acceptability and hardness.