Preparation and Quality Evaluation of Flour and Biscuit from Sweet Potato

Abstract

The effect of extrusion conditions, including feed rate (20-32%), feed moisture content (14-22%), screw speed (180-320 rpm), and barrel temperature (100-140 °C) on the physicochemical properties (density, expansion, water absorption index - WAI), and water solubility index (WSI) and sensory characteristics (hardness and crispness) of an expanded rice snack was investigated. Increasing feed rate results in extrudates with a higher expansion, lower WSI, and higher hardness. Increasing feed moisture content results in extrudates with a higher density, lower expansion, higher WAI, lower WSI, higher hardness and lower crispness. Higher barrel temperature increased the extrudate expansion but reduced density, increased the WSI and crispness of extrudate. Screw speed had no significant effect on the physicochemical properties and sensory characteristics of the extrudate. © 2004 Elsevier Ltd. All rights reserved.