ABSTRACT

Some engineering properties of cassava tuber related to its peeling mechanization were determined five varieties of cassava namely: The Pro-Vitamin A Cassava- Umudike Cassava (UMUCAS 36, 37 and 38) also known as Tropical Manihot Specie TMS 01/1368, 01/1412, 01/1371 respectively, and National Roots (NR 8082 and 98/0581. The engineering properties determined were physical and mechanical properties. The physical properties includes moisture content, size (tuber and peel thickness ), geometric mean diameter, arithmetic mean diameter, surface area, aspect ratio, mass, volume, true density, bulk density, porosity. The mechanical properties- angle of repose and coefficient of static friction of both peeled and unpeeled samples. The results showed that the highest moisture content at which the experiment was carried out was 84.33+1.96% while the lowest was 63.50±3.33%. The tuber thickness at major diameter "a" had the largest 64.43±14.22mm, the smallest average head diameter was 60.40±9.62mm. Intermediate diameter "b", the largest value was 60.90±11.72mm (UMUCAS 36), the least 50.43+9.43mm (NR 8082). For the average minor diameter "c", the maximum value was 40.27+11.76mm(UMUCAS 36), the minimum was 28.67+6.58mm(NR 8082). UMUCAS 38 is the longest and has the largest major diameter than the varieties tested. NR 09/058 1 has the highest peel thickness than the whole varieties and NR 8082 has thin peel thickness. NR 8082 is more regular than the rest with average sphericity of 73.45 ±6.3 8. For average mass, UMUCAS 36 is greater than UMUCAS 38 > UMUCAS 37 > NR 09/058 1 > NR 8082. All the varieties are denser than water and thus sinks inside water except UMUCAS 37 which is slightly less dense which can float on water NR 8082 is more porous than the other varieties with porosity of 40.86%. The angle of repose of the peeled cassava is lower than the unpeeled cassava which shows that the peeled cassava is smoother than the unpeeled cassava. Coefficient of static friction for unpeeled cassava tubers for the metal surface, the maximum was 4.3±3.03 (UMUCAS 36) and the minimum average value was 1.77±0.3 1 (UMUCAS 37). For peeled cassava tubers, coefficient of static friction on metal surface had the maximum value 7.08±3.03 (NR 8082) and the minimum average value was 1.62±0.37 (NR 98/058 1).