Effect of extrusion on physical and functional properties of millet based extrudates: A review

Abstract

The aim of this review is to highlight the effect of extrusion on physical and functional properties of millet based extrudates. Extrusion is a combined thermo-mechanical process which causes gelatinization, breakdowns complex starch and protein structure of the food in short span of time. Merely changing the process conditions of the feed composition and moisture content, the cooking temperature along the extruder and the die and screw speed gives a variety of desired product. Various researchers have formulated different millet-based extruded snacks using pearl millet, finger millet, foxtail millet, kodo millet and sorghum and/or supplementation of major cereals and pulses. The studies shows the significant effect of machine and material parameters on physical and functional properties of extrudates including, expansion ratio, bulk density, water solubility index, water absorption index and specific length.