Abstract:
Starch is a polymer of glucose found in most plant. It belongs to the class of organic compound called carbohydrates, which comprising of carbon, hydrogen and oxygen. It is produced from raw materials like maize, wheat, rice or cassava. The advantages of cassava starch over grains and other root crops starches include high concentration of starch on dry-matter basis. Most of the cassava starch extraction machines used is manually operated without a sieving mechanism which rendered the products not widely acceptable. The development of cassava starch extraction machine is essential at this time because of its high level of purity and desirable textural characteristics. A cassava starch extraction machine that is easy to assemble, operate and maintain was developed. The major components of the machine are hopper, mixing unit, extraction chamber which houses the screw conveyor (auger) and sieve, discharge outlets and the power units. The machine was powered by 2 KW variable gear electric motor. The operational principle of the machine is by feeding the cassava mash and water through the hopper, under gravity the mash and water fall freely into the mixing chamber, power was provided to drive the stirrers and the screw conveyor, the rotated stirrers mixed the slurry properly to the desirable cassava mash: water ratio, the slurry is discharged to the extraction chamber where the conveyor moves and rotate it over a sieve thereby causing the moist starch to liberate. The performance of the machine was evaluated using three stirrers speeds (80rpm, 100rpm and 120rpm) and seven water quantities (10, 12, 14, 16, 18, 20 and 22) litres, to determine the optimum rotational speed of the stirrers and cassava mash: water ratio for maximum production of cassava starch. It was observed that at cassava mash: water ratio of 5Kg TMS 30572 cassava mash to 18litres of water, the throughput t was25.2kg/hr and extraction efficiencywas80%.The optimum performance of the machine was achieved when it was powered by 2 KW variable gear electric motor, and the rotational speed of the stirrers was 100rpm with most appropriate cassava mash: water ratio. The total cost of production of the machine at the time of fabrication was N 66, 100.00K.The machine is therefore recommended for small and medium scale producers of cassava starch
