Single-Screw Laboratory Extruder for Production of Expanded Products: Design, Construction and Performance Testing

In this study, a low-capacity single-screw cooking extruder for the manufacture of expanded snacks was designed based on theoretical models and guided operating data and practices of existing cooking extruders. Construction was carried out using locally available engineering materials in modest machine shops satisfying sanitary design criteria and tested using blends of cassava and defatted soybean flour. The extruder developed has throughput, screw speed, barrel diameter, length-to-diameter ratio and power requirement of 13.0 kg/h, 200 rpm, 40 mm, 12 and 1.908 kW, respectively. The cost of the extruder developed was estimated N650,000 in 2016. Extrudates had expansion ratio and trypsin inhibitor reduction which ranged from 1.82 to 2.98 and 61.07% to 87.93%, respectively, across all treatments. This study demonstrates that a low-capacity and affordable experimental single-screw extruder can be designed and built domestically which can be scaled-up for pilot and industrial applications for the production of expanded snacks.