Influence of the extrusion parameters on the physical properties of chickpea and barley extrudates

In this research, the effects of extrusion processing [exit-die temperature (120-150°C), moisture content (20-24% wet basis), and screw speed (260-340 rpm)] on the specific mechanical energy and physical properties (expansion ratio, bulk density, and hardness) of desi chickpea and hullless barley extrudates were estimated using response surface methodology. Exit-die temperature and feed moisture content, as well as the interaction between them were the factors that affected the product responses the most. Significant correlation was found between the hardness and bulk density (positive), hardness and expansion ratio (negative), and bulk density and expansion ratio (negative) for both chickpea and barley extrudates. Desirable characteristics (high expansion, low bulk density, and hardness) for chickpea were obtained at high exit-die temperature, relatively high moisture, and high screw speed. As for the barley extrudates, high exit-die temperature, low moisture, and moderate to high screw speed were identified as optimal.