Process optimization of extrusion variables and its effect on properties of extruded cocoyam ( Xanthosoma sagittifolium ) noodles.

The current industrial demand for starchy foods has been dominated by other roots and tubers, while cocoyam, despite being rich in fiber, minerals, and vitamins has remained under exploited. In this study, the effect of feed moisture content (FMC), screw speed (SS) and barrel temperature (BT) on the quality characteristics of cocoyam noodles (proximate, thermo-physical, physicochemical, texture, color, extrudate properties, and sensory characteristics) were investigated using central composite design (CCD) of response surface methodology (RSM). Flour was produced from fresh tubers of cocoyam ( Xanthosoma sagittifolium ) and subsequently processed into noodles using a twin screw extruder. Results showed that the proximate compositions, thermo-physical, physicochemical properties, and color of the cocoyam noodles were significantly ( p  < 0.05) influenced by the extrusion process variables. The texture and extrudate properties of cocoyam noodles were equally significantly ( p  < 0.05) different. The experimental data obtained and predicted values of the response models were comparable, with statistical indices [absolute average deviation (AAD, 0-0.23), bias factor ( B f , 1-1.08), and accuracy factor ( A f , 1-1.23)] indicating the validity of the derived models. The optimal extrusion processing conditions for quality cocoyam noodles were FMC, SS, and BT of 47.5%, 700 rpm and 50°C, respectively, as cocoyam noodles obtained at these conditions had comparable properties and were most preferred and accepted by the sensory panelists.