Specific Mechanical Energy Requirement of a Locally Developed Extruder for Selected Starchy Crops

Abstract

In this study, the specific mechanical energy (SME) response of a dry type single screw extruder (Length to Diameter ratio (L/D) 12:1, Compression Ratio (CR) 4.5:1) developed locally was investigated for maize, cassava and wheat flour processing. The study was necessitated by the need to provide management data for the preliminary studies of the extruder A factorial experiment in completely randomized design was employed to study the effect of extrusion variables: feed moisture (25 – 50%), extruder temperature built up by varying the duration of sampling (2 – 30 min) and screw speed (100, 150, 200 rpm) on SME. The study revealed that SME varied directly with duration of operation for cassava products and inversely with duration of operation for all maize and wheat products. SME increased with increasing speed from 100 to 150 rpm but decreased at 200 rpm. SME increased with increase in moisture content from 25 to 40%.