Admassu, Shimelis(Professor)Taye, Abayneh2018-07-132023-11-102018-07-132023-11-102013-06http://etd.aau.edu.et/handle/12345678/8432The study was conducted with the aim of producing protein enriched extruded product that can be used as a protein supplement by combining legumes, cereal and oil seeds. Accordingly, maize, defatted soy flour and chickpea were selected based on their nutritional value, availability in the local market and affordability. By Applying mixture experimental design, formulation containing 589 g/kg corn, 291 g/kg defatted soy flour, and 120 g/kg of chickpea flour was selected as the best source of protein. The effects of extrusion parameters on the specific length, bulk density, and expansion ratio, functional properties (water solubility index, water absorption index and water holding capacity) were done, after extruding the blend with moisture content (17and 20%) barrel temperature (120, 130, and 140 0C), and screw speed (150,200 and 250 rpm). Sensory characteristics of extruded products (texture, color and overall acceptability) were also studied to evaluate the suitability of the product as extruded snack. Using the blend ratio obtained from the design, an extrudate containing 21.34% protein, 2.81 % of fat and 65.06% of carbohydrate was found to be the protein enriched product. The specific length, expansion ratio and bulk density were found highly affected by barrel temperature and moisture content. As the barrel temperature increased from 1200C to 1400C and the feed moisture content kept at 17 %, extrudates with high expansion ratio (146%) and lower bulk density (9%) were found. An increment in barrel temperature from 120 0C to 140 0C was the only parameter that significantly affects (P<0.05) the specific length of the extrudates by increasing from 1.81 to 2.74. Screw speed effect was only seen on the extrusion dependent variables through decreasing torque, die pressure and SME from 24.75 to 12.42, 19.5 to 11.12 and 302.28 to 173.73, respectively. The functional properties ,water solubility index, water absorption index and water holding capacity of the extrudates (4.59, 21.84 and 3.165) were found higher than that of the formulated flour (2.48, 13.49 and 1.59); respectively due to starch gelatinization. Results on the antinutrents studies showed reduction of 20% in phytate and 28% in tannin. The sensory evaluation result showed that extrudate produced with Moisture content of 17%, temperature of 140 0C and screw speed of 200rpm was perceived as the most accepted product. Accordingly a process technology for the production of the snack is suggested. Key words: Chickpea flour, Defatted soy flour, Extrusion, Flake, Maize flour, Mixture DesignenChickpea flourDefatted soy flourExtrusionFlakeMaize flourMixture DesignThesis