Effect of Extrusion Process on Proximate Composition of Water Yam Based Noodles Analogue – A Response Surface Analysis

Response surface methodology was used to investigate the effect of extrusion process on proximate composition of noodles analogue from water yam, yellow maize, and African yam bean flour mixture. Flour blend from water yam, yellow maize, and African yam bean were produced and was used to extrude noodles analogue using a brabender single screw laboratory extruder (Duisburg DCE 330 model) fitted with 3.0mm die nozzle diameter. A central composite rotatable design with three variables, namely barrel temperature, feed moisture content and screw speed and five level coded – a, -1, 0, +1,, +a, was used and data analyzed by regression analysis. Results showed that proteins of noodles analogue ranged from 12.40 to 22.16%; fat content ranged from 2.98 to 6.07%; fibre content ranged from 1.80 to 2.52%; ash content ranged from 6.21 to 9.50%; moisture content ranged from 11.05 to 12.47% and carbohydrate content ranged from 48.31% to 63.65% respectively. The coefficients of determinations (R2) were high and ranged from 0.9106 to 0.9747 at 5% level. The response surface plot suggested that the models developed had a good fit and the CCRD was effective in explaining the effect of the process conditions on noodles analogue as influenced by barrel temperature, feed moisture content, and screw speed of the extruder. The data obtained from the study could be used for control of product characteristics. The study indicated that improved noodles analogue produced from available and cheap roots, cereal and legumes such as water yam, yellow maize, and African yam bean can be produced for possible projection for the commercial production of noodles analogue.