Extrusion Process Optimization for Soy-Carrot Pomace Powder Incorporated Wheat-based Snacks

Abstract

Twin screw extruder was used to develop soy-carrot pomace incorporated wheat-based nutritionally rich snacks. Different experimental combinations of extrusion process variables as die temperature, screw speed, feed moisture and wheat flour in the feed formulation of wheat, defatted soy flour and carrot pomace powder, were tried using Box-Behnken design of experiment. Response surface methodology (RSM) was used to investigate the effect of die temperature (120-180°C), screw speed (300-500 rpm), feed moisture (14-20%) and wheat flour (65-85%) with soy-carrot pomace blend in equal proportion on product responses like bulk density (BD), water absorption index (WAI), water solubility index (WSI), hardness (H), colour change (CC), and overall acceptability (OA). The extrusion process was optimized for maximum expansion ratio, water absorption index, water solubility index and overall acceptability; and minimum bulk density, hardness and colour change within the experimental range. Analysis of variance (ANOVA) revealed that among the process variables, feed moisture and wheat flour percentage in feed formulation had significantly higher effect on BD, ER, WSI, CC and OA. Die temperature was observed to have significantly lower effect on the selected responses. The optimized extrusion conditions for desired product quality had desirability of 0.729.