Development and evaluation of extruded ready-to-eat snack from optimized rice, kersting's groundnut and lemon pomace composite flours.

Abstract

Composite flour comprising rice, kersting's groundnut and lemon pomace were produced. The percentage blends of the composite flours based on the proximate composition and functional properties were optimized using optimal mixture design of response surface methodology (RSM). The optimum blends were subjected to further analyses (pasting properties and Mixolab). The overall best blend was selected for extrusion. The extrusion process was optimized using central composite design of RSM. The variables were moisture content, screw speed and temperature while the dependent variables were lateral expansion, residence time, throughputs, water absorption index and water solubility index. The microbial analysis as well as the sensory evaluation of the extrudates was also evaluated. The result showed that addition of kersting's groundnut had positive effect on the protein content while lemon pomace had positive effect on bothfibre and protein contents. Blend with highest rice flour had the best pasting properties. The Mixolab results had C1 stage similar to wheat flour while it had no C2-C5 stages. The optimum blend for extrusion was 97°C barrel temperature 12% moisture and 90rpm screw speed which present the best lateral expansion, water absorption index and water solubility index. All the snacks had high general acceptability.