Cassava Mash Process Handling

Abstract

Several efforts have been made to develop suitable indigenous machines for cassava processing; this attempt was made to make the cassava mash process more energy-efficient and to meet the Millennium Development Goals (MDGs), aimed at poverty reduction over a stipulated period of time. A suitable machine was developed to handle cassava mash processing in High Quality Cassava Flour (HQCF) production. The development was done by using basic scientific outcomes, engineering discoveries, well-known principles and existing cassava mash handling practices in HQCF production. The development involves survey of existing methods, conceptual design sketches, components design, machine drawings, calculations, prototype fabrication and testing. The laboratory investigations were carried out on handling and materials interactions with the cassava mash containing starch and fibre. Mash flowability on steel, plywood and Aluminum was conducted. Resistance of cassava mash to applied pressure during filtration and expression dewatering was handled with steady volume reduction process. A pressure setting for first stage of dewatering was based on the back pressure crated by spring with a known force. Screw conveying capacity reduction creates pressure as a result of tapered shaft. The parameter settings were determined experimentally before the combination of the operating units. Results of test carried out gave a mash residing time of 7minutes. The emerging mash paste from the screening unit contains 57%mcwb from 72% mcwb cassava mash sample. Further movement of the mash paste was accomplished with continuous variable volume expression dewatering. The final obtained mash cake has a moisture content of 43-48% mcwb. The mash cake formation depends on the strength of the back up spring. Pulverization unit receives mash cake through gravity via conveying tube inclined at 45 degree. A high-speed size reduction unit breaks the mash cake into particles then allows it to flow out into a reciprocating sieve. The machine produces the desired mash of fine particles less than 1mm thickness ready for flash drying. The combined handling movements resulted in using small space, reducing unnecessary human handling, it eliminates drudgery. The prototype was powered with a single 35W electric motor there by minimizing the power requirement; the product obtained compared well with the existing HQCF mash data. The machine product could perform better than the local ones at a reasonable time when commercially adopted.