Effect of Extrusion Process Parameters on Physical, Functional and Textural Properties of Broken Rice-Foxtail Millet-Maize based Extrudates

Abstract

The effect of extrusion on the physical, functional and textural properties of broken rice extrudates blended with foxtail millet and maize flours of various formulations (10:80:10, 20:60:20, 30:40:30, 10:60:30 and 30:60:10) on density, true density, porosity, expansion ratio, water absorption index (WAI), water solubility index (WSI), solubility index, swelling power, colour values, hardness and fracturability by varying the parameters of feed moisture content, screw speed and barrel temperature were investigated. The density of blends ranged from 0.09 to 0.57 g/cm3 , expansion ratio (1.47-2.58), true density (40.08-559.48 kg/m3 ), porosity (22.83-38.18 per cent), WAI (3.52-7.81 g/g), WSI (0.0-6.6 per cent), swelling power (5.03-8.18 g/g) and hardness (1.91-10.44 N). It was observed that the increase in feed moisture content resulted in extrudates with a lower expansion ratio and WAI, higher density, WSI and hardness. Among the various combinations investigated the blend with broken rice (30), foxtail millet (60) and maize (10) yielded good sensory results. The results obtained from the experiments were significantly different at (P≤0.01) all combinations.