Effect of screw configuration and raw material on some properties of barley extrudates

Twin-screw extrusion was performed to evaluate the potential use of barley grits and barley flour for expanded snack foods. The 2 × 2 factorial design had two levels of raw material (barley grits and barley flour) and two levels of screw configuration severity (medium and severe). The experimental responses were the following extrudate properties: specific mechanical energy (SME), expansion (SEI), bulk density, water absorption index (WAI), hardness, breaking strength and color. Means of the responses were significantly different for all responses except bulk density and WAI with respect to screw configuration. For raw material, the means of the responses were significantly different for all responses except SEI and WAI. Barley flour extrudates produced by severe screw configuration had significantly lower SME than barley grits extrudates. Severe screw configuration produced more expanded product with low bulk density than that of medium screw configuration. Correlations were found between product responses.