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Effects of the extrusion processing variables on the physical properties of chickpea-barley extrudates
A. STONE (1), A. Yovchev (1), M. Nickerson (1), S. Hood-Niefer (2) (1) University of Saskatchewan, Saskatoon, SK, Canada; (2) Saskatchewan Food Industry Development Centre Inc., Saskatoon, SK, Canada.

The effects of extrusion processing variables [barrel temperature (120-150°C), moisture content (20-24% wet basis) and screw speed (260-340 rpm)] on the specific mechanical energy (SME) and physical properties (expansion ratio, bulk density and hardness) of chickpea-barley extrudates were estimated by using a response surface analysis. The extrudates were prepared from a 60:40 (w/w) blend of desi chickpea and hull less barley flours. The extrusion was performed using a co-rotating twin-screw extruder with a length: diameter ratio of 24:1. Barrel temperature and moisture content were the factors that affected the product responses the most. No interaction between the effects was observed. Significant correlation was found between the hardness and bulk density (positive), hardness and expansion ratio (negative), and the bulk density and expansion ratio (negative) of the extrudates. Desirable characteristics (high expansion, low bulk density and hardness) were obtained at relatively low moisture, high temperature and moderate to high screw speed.