Effect of hydrocolloids and process variables on the extrusion behaviour of rice grits

Investigations were carried out to study the effects of incorporating vario us hydrocolloids viz., carboxymethyl cellulose (CMC), sodium alginate and g um acacia at different levels (1, 2 and 3%) and processing variables such a s feed moisture and barrel temperature on the extrusion behaviour and produ ct characteristics of rice grits. Specific energy consumption (SEC) decreas ed with increase in the levels of all types of hydrocolloids. Die pressure of extruder progressively increased with the increase in the level of sodiu m alginate and CMC, while the reverse was true for gum acacia. Expansion ra tio and water absorption index (WAI) increased whereas, density decreased w ith the addition of all types of hydrocolloids. However, the intensity of i ncrease in WAI varied with the type of hydrocolloid. Viscosity of ground ex trudates increased with the addition of CMC and decreased with sodium algin ate and gum acacia. Feed moisture and barrel temperature showed pronounced effects on the viscosity of all extrudates.