Food and Nutrition Sciences, 2014, 5, 1309-1317 Published Online August 2014 in SciRes. http://www.scirp.org/journal/fns http://dx.doi.org/10.4236/fns.2014.514142 How to cite this paper: Omwamba, M. and Mahungu, S.M. (2014) Development of a Protein-Rich Ready-to-Eat Extruded Snack from a Composite Blend of Rice, Sorghum and Soybean Flour. Food and Nutrition Sciences, 5, 1309-1317. http://dx.doi.org/10.4236/fns.2014.514142 Development of a Protein-Rich Ready-to-Eat Extruded Snack from a Composite Blend of Rice, Sorghum and Soybean Flour Mary Omwamba * , Symon M. Mahungu Department of Dairy, Food Science & Technology, Egerton University, Egerton, Kenya Email: * marynyambeki@yahoo.com Received 22 May 2014; revised 25 June 2014; accepted 8 July 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Extrusion cooking is an ideal method for the manufacture ready-to-eat snacks. The benefits in- clude increased protein and starch digestibility in protein-enriched cereal snack products. Extru- sion cooking needs to be controlled if product quality is to be maintained. Extrusion cooking was carried out at barrel temperature of 110˚C - 150˚C, screw speed of 350 - 450 rpm, and feed mois- ture of 12% - 14% to investigate the effect of extrusion conditions on physical properties (expan- sion ratio and bulk density) of a rice, sorghum and soy flour blend. From response surface analysis, expansion ratio and bulk density were found to be significantly (P < 0.05) dependent on feed moisture and barrel temperature while the screw speed had a significant (P > 0.05) effect. Expan- sion ratio and bulk density ranged from 2.0 to 2.6 and 0.79 to 0.95 g/ml respectively. One hundred grams of the extruded product would supply 45% of the recommended daily allowance for protein in children aged up to 12 years. The mineral content in 100 g extrudates was found to be 52 mg calcium, 3.01 mg iron and 1.23 mg zinc. The retention of amino acids in the extruded products was 88% - 95% with lysine—a limiting amino acid in cereals having a loss of 9.1% after extrusion. Ex- trusion conditions can be optimized to produce ready-to-eat snack products with high expansion ratio, low bulk density and a good nutritional profile to meet the growing consumer needs for nu- tritious ready-to-eat snack products. Keywords Rice, Sorghum, Soybean, Extrusion, Response Surface Methodology, Snacks 1. Introduction There is a growing consumer interest in ready-to-eat snack foods mainly due to their convenience, wide availa- * Corresponding author.