Effect of extrusion conditions on the physical properties of desi chickpea-barley extrudates and quality attributes of their resulting flours.

In this study, response surface methodology (RSM) was used to evaluate the effect of extrusion conditions on physical properties of chickpea:barley extrudates (60:40), and the resulting protein quality of their flours. Barrel temperature (150-170°C) and moisture content (16-20%) were chosen as independent variables to generate a central composite design. Hardness, expansion index, bulk density, and protein quality were analyzed as responses parameters. Expansion was found to be higher at lower temperatures and higher moisture for the 60:40 chickpea:barley blend; bulk density became reduced with increased moisture; and hardness was found to increase at higher temperatures and lower moistures. The protein quality of their resulting flours was found to be greater at moisture contents higher than 16%. The composition, protein quality, and functional attributes were also examined for raw and precooked flours of chickpea, barley, and their blend at the center point of the RSM design (18% moisture, 160°C). Extrusion also leads to improved water hydration capacities and reduced viscosities for precooked individual and blended flours relative to the raw. Moreover, extrusion also led to improved protein quality in the chickpea and chickpea-barley blend, but not the individual barley flour.