Process optimization of extrusion variables and effects on some quality and sensory characteristics of extruded snacks from whole pearl millet-based flour
Sunday Samuel Sobowale, Yusuf Olamide Kewuyemi, T.M.A. Olayanju
Abstract
This study investigated the effects and optimization of the respective feed compositions of pearl millet flour (PMf), African walnut flour (AWf), and corn starch (CS) [FC, (100:0:0, 90:5:5, and 80:10:10)], feed moisture content [FMC, (10, 15, and 20%)] and barrel temperature [BT, (60, 70, and 80 °C)] on some quality characteristics of extruded snacks using Box-Behnken design. The AWf and CS were substituted at 0, 5, and 10% in PMf and evenly mixed with sterile water to attain the required FMC. The resultant dough was processed in a twin-screw extruder into whole pearl millet-based snacks. The results showed that the extrusion variables significantly influenced (p < 0.05) the quality and extrudate properties examined. The good fits of the response models were affirmed favourably by the adequacy of the coefficient of determination (> 0.90), absolute average deviation (≤ 0.05), accuracy factor (≤ 1.05), and bias factor (≤ 1.01). The optimization of the combined interactive effects on an extruded snack prepared using 80% PMf, 10% AWf, and 10% CS cooked with 15% FMC at 60 °C BT gave desirable crude protein, fat, fibre contents with complementary low residence time, increased expansion ratio, and was liked moderately by the sensory panellists. Pearl millet-based snacks could be a worthy alternative to gluten-free snacks.