Process parameter optimization for textural properties of ready-to-eat extruded snack food from millet and legume pieces blends

Abstract

Five blends of millets and legume pieces (viz. 12, 16, 20, 24, 28% legume pieces) at varying moisture contents (12, 15, 18, 21, 24%, wet basis [w.b.]) were subjected to extrusion cooking in a single-screw laboratory extruder Brabender DA47055. The extruder was operated at different die head temperatures (160-200C), barrel temperatures (100-140C) and screw speeds (100-140 rpm). Designed experiments were conducted based on central composite rotatable design to determine the optimum processing condition for extruded products. The processing parameters were optimized with the help of response surface methodology to obtain product with maximum crispness and with minimum hardness and cutting strength. The optimum processing conditions obtained were moisture content 24%, w.b.; blend ratio 18.7% legume pieces; die head temperature 171.2C; barrel temperature 140C; and screw speed 103.8 rpm. The corresponding textural properties of the extrudates in terms of crispness, hardness and cutting strength were 50, 48.2 N and 79.7 N, respectively. © 2009, Wiley Periodicals, Inc.