A COMPREHENSIVE & PRACTICAL GUIDE ON HOW TO START CASSAVA FARMING & PROCESSING BUSINESS By : Micheal B . O .
then be easily removed . Any dirt remaining on the smooth surface of the core of the tuber can be washed off without any trouble and the peeled tubers can be deposited in cement basins where they will remain immersed in river water until taken out for rasping . In the larger factories , whole tubers are generally processed . The washing here serves to remove the outer skin of the tubers as well as the adhering dirt . Provided the tubers are sufficiently ripe , the skin may be removed without the use of brushes . Only the outer skin or corky layer is removed , as it is profitable to recover the starch from the cortex . The inner part of the peel represents about 8 % to 15 % of the weight of the tuber .
RASPING AND PULPING
One has to rupture all the cell walls in order to release the starch granules . This can be done by biochemical or mechanical action . The biochemical method , an old one , allows the tubers to ferment to a certain stage . Then the roots are pounded to a pulp from which the starch is washed with water . This method does not give complete yields and the quality of the resulting starch is inferior . Mechanical action requires the roots to be and then rasped , grated or crushed , which tears the flesh into a fine pulp .
By pressing the tuber against a swiftly moving surface provided with sharp protrusions , the cell walls are torn up and the whole of the tuber is turned into a mass into which the greater part , but not all , of the starch granules is released . The percentage of starch set free is called the rasping effect . Its value after one rasping may vary between 70 % and 90 %. The efficiency of the rasping operation therefore to a large extent determines the overall yield of starch in the processing . It is difficult to remove all the starch in a single operation , even with efficient rasping devices . Therefore , the pulp is sometimes subjected to a second rasping process after screening . The rasping is carried out in different ways and with varying degrees of efficiency .
HAND AND MECHANICAL RASPING
On tiny smallholdings in some cassava-growing regions , the tubers are still rasped by hand on bamboo mats . Where daily production amounts to several hundred kilograms of flour , basic mechanical implements are used .
GRADING Cassava is graded into three classes or sizes , namely large , medium and small . The tubers are also separated according to quality . Those of good quality are free from any bruises and cuts and those of poor quality are usually not saleable and are normally given away or used as feeds . The perception of good-quality cassava among buyers is that it is bigger in size , fresh and free from rotting .
PACKING In Africa there are also a number of traditional systems involving cassava storage in pits or clamps . Fresh tubers are generally processed on the day that they arrive at the factory and it is rare to find industries that have storage facilities . Cassava processing industries that use dried
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