Characterizing the Specific Mechanical Energy Requirement for Maize and Cassava Processing from a Locally Developed Extruder Folasayo T. Fayose 1 * and Leo A. S. Agbetoye 2 1 Department of Agricultural Engineering Technology, Rufus Giwa Polytenic, P.M.B.1019, Owo, Nigeria. 2 Department of Agricultural Engineering, Federal University of Technology, P.M.B.704, Akure-Nigeria *Corresponding author E-mail: fayosesayo@yahoo.com Abstract In Nigeria, energy issues are now receiving considerable attention as its cost of production is increasing by the day. Also, Extrusion cooking is a versatile process that helps in the expansion of the processing technology of crops. In this study, the response of Specific mechanical energy (SME), a common measure of extrusion energy (consumption of a dry type single screw extruder (L/D 12:1, C/R 4.5:1) developed locally was investigated. The study considered the extrusion process of the flour and starch of maize and cassava which are grown in Nigeria in large quantity and wheat flour which is commonly used for the production of alimentary pastes. In this study, the response of Specific mechanical energy (SME), a common measure of extrusion energy consumption of a dry type single screw extruder (C/R 4.5:1, L/D 12:1) developed locally was investigated. The study considered the extrusion process of the flour and starch of maize and cassava which are grown in Nigeria in large quantity and wheat flour which is commonly used for the production of alimentary pastes. A factorial experiment in completely randomized design was employed to study the effect of extrusion variables: feed moisture (30, 40, 50 %), extruder temperature built up by varying the duration of sampling and screw speed (100, 150, 200 rpm) on SME. Also, the order of importance of the variables was determined with stepwise regression analysis. The study revealed that SME varies directly with duration of operation for cassava products and inversely with duration of operation for all cereal pr under consideration. SME decreased with increase in duration of operation. Also, it increased from 100 to 150 rpm and then decreased at 200 rpm. Extruder’s performance improved from 100 to 150 rpm but at 200 rpm there was a change in the performance of the extruder. For instance, the product temperature reduced at 200 rpm than at 150 rpm. Also, the SME decreased as screw speed increased. Also, SME decreased with increasing speed from 100 to 200 rpm and increase in moisture content from 25 to 40%. Maximum SME of 241.71 kJ/kg was attained in 30 minutes through viscous dissipation at 150 rpm and 30% moisture content by cassava starch while a minimum of 4.7 kJ/kg occurred at 200 rpm and 40% moisture content and 30 minutes duration for maize starch. However, SME varies inversely. The stepwise regression data analysis of SME show that interaction term of ths starch content and moisture content has the highest contribution 15.9%, to R 2 of SME. The variable, starch content accounted for 2.9%, duration of sampling, 3.9% of the total variation in R 2 and the interaction of duration of operation, starch and moisture contents accounted for only 1.4%. Although, a 4 kW electric motor was used for this experiment, the study revealed that an extruder with less power requirement will be appropriate for maize and wheat extrusion, thus reducing cost. Key words: Extrusion, Fish feed, Cassava flour, Quality parameters, Nigeria 1. Introduction The amount of energy used for processing raw products into consumable goods has been only narrowly explored for specific commodities. The amount of energy used in agricultural production, processing and distribution is significantly high in order to feed the expanding population and to meet other social and economic goals of society. Sufficient availability of the right energy and its effective and efficient use are prerequisites for improved agricultural production [1],[2]. In Nigeria, energy issues are now receiving considerable attention as its cost of production is increasing by the day. Also, Extrusion cooking is a versatile process that