Optimization of extrusion processing conditions for preparation of an instant grain base for use in weaning foods

The purpose of this study was to investigate the effect of process conditions on the properties of instant grain base. A blend of wheat, mungbean and groundnut was used in the study. The effects of feed moisture, barrel temperature and screw speed on product responses viz. specific mechanical energy (SME), expansion ratio (ER), density (D), water absorption index (WAI) and water solubility index (WSI) was studied using response surface methodology.The blend was extruded at different moisture content (12.6 -19.4%), screw speed (349 601 rpm) and barrel temperature (116 184°C). The regression models for SME, expansion ratio, bulk density, WAI and WSI were highly significant. SME has been found to decrease with increase of moisture and temperature and increased with increase in screw speed. Expansion ratio and density were significantly affected by feed moisture and temperature. WAI and WSIwere found to decrease significantly with increase in moisture content and increased significantly with increase in Screw speed and temperature.The optimum values for moisture content, screw speed and temperature were 14.08%, 521 rpm and 140 o C respectively. The desirability was found to be 0.835 for this model.