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DEVELOPMENT OF SORGHUM (Sorghum Bicolor) AND RAGI (Eleusine Coracana) BASED READY-TO-EAT SNACKS USING TWIN SCREW EXTRUDER

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010  1009052.(doi:10.13031/2013.29793)
Authors:   SRINIVASA RAO PAVULURI, Ravi Kumar M
Keywords:   Twin Screw Extruder, Ready-to-eat snacks, Sorghum, Ragi, Response Surface Methodology.

Extrusion cooking is used world wide for the production of expanded snack food, modified starch, ready-to-eat cereal foods. Product quality can vary considerably depending on extruder type, screw configuration, feed moisture, barrel temperature, screw speed, die profile, feed rate and composition. Sorghum (Sorghum bicolor) and Ragi (Eleusine coracana) are the economical and important cereal and millet grains which have high nutritive values. Their utilization is confined mainly to the poorer section of the population in developing countries, and a need exists to diversify their use by developing ready to eat snack foods. Extrusion of sorghum flour and ragi flour was carried out to study the effect of various extrusion operating parameters (barrel temperature, screw speed, moisture content, feed rate, sorghum-ragi flour blend percent) on the properties of extruded snack viz. product density (PD), expansion ratio (ER), water solubility index (WSI), water absorption index (WAI), crispness and hardness using twin screw extruder. Temperature was the most influencing parameter followed by moisture content whereas Screw speed and feed rate were found to be having least influence on extrudate properties. Decrease in moisture content with increasing temperature resulted in decrease of PD. Combination of high temperature and high screw speed yielded a product with low density. Expansion increased with increasing screw speed. WSI was found to be decreasing at higher moisture levels. Optimization was done for minimizing the product density, WSI, hardness and maximizing expansion ratio, crispness and WAI. The optimum conditions found were barrel temperature 1150C, screw speed 279 rpm, M.C. 11.75%, flour blends of sorghum 70%+ragi 30% and feed rate 24.79 kg/hr, which resulted in the product with PD 104.49 kg/m3, ER 14.06, WSI 15.54%, WAI 8.65, crispness 7, hardness 5.14 N and final moisture content 4.92% (wb).

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