Extrusion of blends of rice and chick pea flours: A response surface analysis

Abstract

Blends of rice and chick pea ( Cicer arietinum) flours, containing 20% moisture, were extruded through a single-screw extruder. The extrusion process variables were: (i) feed ratio (ratio of the solids of rice and chick pea flour=100:0, 90:10 and 80:20), and (ii) temperature of die (100, 125 and 150°C). The torque during extrusion was measured, so also were product characteristics, such as expansion ratio, bulk density and shear strength. Response surfaces for these parameters were generated using a second degree polynomial. Incorporation of chick pea into rice flour decreased torque and product expansion, but increased bulk density and shear strength. The temperature of the die had a linear effect on these parameters. Optimum extrusion conditions — resulting in minimum torque and bulk density — were estimated. Sensory assessment of the extruded samples fried in oil indicated that extrusion of rice or rice-chick pea blends could be an alternative method of producing acceptable snacks.