Abstract

A three-factor three level response surface methodology central composite retortable design (CCRD) was adopted to study the effect of feed composition (X₁), feed moisture content (X₂) and screw speed (X₃) on the proximate, amino acid composition and sensory evaluation during extrusion of pearl millet and cowpea flour mixtures for the purpose of fura production. The mean observed value of protein for the fura-extrudates ranged from 11.23 to 16.76%. Analysis of variance indicates that linear and quadratic effects significantly (P < 0.05) affected the protein content of fura-extrudates. The mean value of lysine for the extrudates ranged from 5.11 to 6.56 g/100g protein and the methionine content ranged from 1.34 to 3.77 g/100 g protein. The regression models fitted to the experimental data showed high coefficients of determinants with R² = 0.96, 0.94, 0.94, 0.85 and 0.80 for protein (CHON), carbohydrate (CHO), fat (FAT), ash (ASH) and water (HOH) respectively. The R² values were 0.90, 0.85, 0.86, 0.92, 0.88, 0.85 and 0.93 for lysine, isoleucine, leucine, valine, methionine-cysteine, threonine and tryptophan, respectively. The coefficients showed good fit. 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 (X₁) >Feed Moisture (X₂) >Screw Speed (X₃). The protein quantity and quality of fura was increased in terms of amino acid profile which justified the reason for fortification of millet with cowpea for fura production. The data obtained from the study can be used for the control of product characteristics and possible projection for the commercial production of fura or any enriched protein based food from the blends of pearl millet and cowpea.

Key words: Millet, cowpea, extrusion, fura, protein, amino acid, feed composition.