Wudpecker Journal of Food Technology 2013 Wudpecker Journals Vol. 1(5), pp. 074 – 092, August 2013 Application of response surface methodology for the evaluation of proximate composition and functionality of millet-soybean fura extrudates 1 K. B. Filli, 2 I. Nkama, 3 V. A. Jideani, 2 U. M. Abubakar 1 Department of Food Science and Technology Federal University of Technology Yola, PMB 2076 Yola, Nigeria. 2 Department of Food Science and Technology University of Maiduguri PMB 1069 Maiduguri, Nigeria. 3 Department of Food Technology, Cape Peninsula University of Technology, Bellville 7535, Cape Town, South Africa. *Corresponding author E-mail: kbfilli@yahoo.com. Accepted 15 June 2013 Fura is a traditional thick dough ball snack produced principally from millet or sorghum which is common in Northern Nigeria. It is consumed with nono (traditional yoghurt produced from cow milk) or mashed in water before consumption in the form of porridge. A three-factors of three level central composite retortable design CCRD was adopted to study the effect of feed composition (X 1 ), feed moisture content (X 2 ) and screw speed (X 3 ) on proximate compositin and amino acid during extrusion of pearl millet and soybean flour mixtures for the purpose of fura production. Extruded fura was produced from pearl millet and soybean, blends using a single screw extruder. Regression models were developed to predict the variables. The result of proximate composition shows that protein, carbohydrates, fat, ash and moisture were significantly influenced by the linear, quadratic and interaction terms of independent variables (p<0.05), with R 2 = 0.96, 0.96, 0.94, 0.79 and 0.80, respectively. The coefficients showed good fit for the model. Regression models for data were significant (P<0.05) with satisfactory coefficients of R 2 for lysine, leucine, Isoleucine, valine, threonine and tryptophan which were 0.92, 0.95, 0.79, 0.88, 0.83 and 0.71; the coefficients shows good fit. The effect of extrusion conditions on water absorption index (WAI) was influenced by liner and quadratic terms significantly (p<0.05). The water solubility index (WSI) was equally influenced significantly by linear and quadratic terms, (p<0.05). Extrusion conditions affected the expansion ratio (ER) by the linear term and bulk density (BD) by both linear and quadratic terms significantly (p<0.05). The models showed good fit with R 2 = 0.92 and 0.96 for ER and BD respectively. The CCRD was effective in optimizing the process condition for fura as influenced by feed composition, feed moisture and screw speed. The importance of process variables on system parameters and physical properties could be ranked in the following order: Feed Composition (X 1 ) > Feed Moisture (X 2 ) > Screw Speed (X 3 ). The protein quantity and quality of fura increased interms of amino acid profile which justified the reason for fortification of millet with soybean for fura production. Extrudates showed the potential of absorbing water as much as at least four (4) times their weight which is an indication of improved functionality of the product. Key words: Millet; Soybean, extrusion, fura, protein, amino acid, functionality. INTRODUCTION Pearl millet (Pennisetum glaucum [L.] R.Br.) is grown extensively in the dry areas of western and southern India and along the West African sub region where it is used as food for an estimated 400 million people (Hoseney et al., 1992). Pearl millet [Pennisetum glaucum] is a cereal used as a food grain, with an estimated 64 million acres of pearl millet being grown in Africa and India. It is known to have a higher protein content and better amino acid balance than sorghum (Dendy, 1995). It is grown mostly in regions of low rainfall and is capable of withstanding adverse agro climatic conditions. Several food preparations are made from pearl millet in Africa and India (Vogel and Graham, 1979; Subramanian and Jambunathan, 1980a). Although carbohydrates are their main contribution, they also provide proteins and other nutrients like fats, fiber, vitamins and minerals. It is