OPTIMIZATION OF EXTRUSION PROCESS PARAMETER FOR DEVELOPMENT OF MAIZE-FINGER MILLET BASED SOY FORTIFIED EXTRUDED PRODUCT

BACKGROUND: Extrusion process parameters are most influencing factors on qualities of expanded product. Small variation in the process parameter can alter the physical, textural and functional properties of product. Extruded products were developed from locally available maize, finger millet, elephant foot yam and defatted soy composite blend (40:30:10:20). Response surface methodology was used to study the effect of barrel temperature (100-150°C), screw speed (110-350 rpm) and feed moisture content (12-20%) on product quality of extruded product. RESULTS:The quality parameters studied were product moisture content (PM), expansion ratio (ER), bulk density (BD), hardness (H), crispness (Cr), water absorption index (WAI) and water solubility index (WSI) The responses were significantly affected by barrel temperature, screw speed and feed moisture content. The feed moisture content had positive and barrel temperature had negative effect on PM, BD, hardness and WAI whereas reverse effect on ER, crispness and WSI. Optimum combination of process parameters suggested was: feed moisture content 14%, barrel temperature 110°C and screw speed 301 rpm. CONCLUSION: The extruded product developed at optimum extrusion condition of 14% feed moisture content, 110°C barrel temperature and 301 rpm screw speed was found to be the best quality. The quality parameters of extruded product obtained were PM 6.76%, ER 2.87, BD 0.17 g cm-3, H 12.91 N, Cr 24.06 fractures, WAI 6.45 g g-1 and WSI 19.87%.