Sensory Evaluation of Instant Noodles Produced from Blends of Sweet Potato, Soybean and Maize Flour

Abstract

Wheat flour is unique for noodles production, but due to high cost, its continuous use in a developing economy is no longer encouraged. This study was aimed at determining the effects of substitution of non-wheat flour on the sensory properties of noodles. D-optimal mixture process experimental design of the responsesurface methodology (RSM) was employed. Thirty-nine (39) samples of noodles were formulated with each blend of sweet potato, soybean and corn flour. The design constraints for the formulations are sweet potato flour (10%<x1<61%), soybean flour (5%<x2<20%), corn flour (5%<x2<30%), and water (25%<x4<37%).Other components of the formulation are salt (2.5%), sodium carbonate (0.5%), guar gum (0.5%), and Soy lecithin (0.5%). The processing parameters cosidered are mixing duration (2min<z1,10min), frying duration (1min<z2<3min) and frying temperature (140°C<z3<160°C). The formulated instant noodles were subjected to sensory evaluation by a panel of semi-trained panelists who had eaten noodles for a long time, and the best formulations were determined in accordance with a preference test. Optimization analysis on the data obtained from the sensory session showed that blend of sweet potato flour (23.305%), soya bean flour (28.529%), corn flour (18.021%), water (26.145%), 2.749 minutes mixing time, 1.35minutes frying time, and 140°C frying temperature, with the highest desirability index of 0.723, produced the best composite instant noodles in terms of taste, texture, flavour, appearance, and overall acceptability. The proximate compositions, cooking, physical and sensory properties of this optimal formulation were: moisture content (13.17%), ash content (6.616%), crude protein (22.862%), energy value (37.707%), crude fat (16.001%) and, crude fibre (4.643%), cooking time (5.415 minutes), cooking weight (26.449 g), water absorption index (164.49), bulk density (0.77), taste (6.406), texture (8.253), flavour (7.659), appearance (6.224), and overall acceptability (5.333). The mixture-process design (D-optimal) was used to establish the effect of changes in mixture compositions and the three processing factors on the main proximate, cooking and physical qualities of instant noodles. The effects were evaluated through analysis of variance at 5% level of significance. The quadratic x mean model for taste, the reduced special cubic x cubic model for texture, the reduced special cubic x cubic model flavour, the quadratic x mean model for appearance, and the quadratic x mean model for overall acceptability were all found to be statistically significant (p<0.05).