Author: Igwillo Ugochukwu Clifford
Department: Agricultural and Bioresources Enigeering
Affiliation: Nnamdi Azikiwe University Awka
This study was carried out to determine physical and aerodynamic properties of African breadfruit (Treculia africana) seeds. Four levels of moisture content: 12.50, 15.00, 17.50 and 20.10% wet basis (w.b) were used in the study; while a sample of African breadfruit seeds at 10.50% (w.b) was used as the control experiment. The physical properties studied were: weight, axial dimensions, geometric mean diameter, arithmetic mean diameter, equivalent diameter, surface area, sphericity, projected area, aspect ratio, volume, true density, bulk density and porosity; while aerodynamic properties studied were terminal velocity, drag coefficient and drag force. As moisture content increased from 10.50 to 20.10% (w.b), the average weight, length, width, thickness, geometric mean diameter, arithmetic mean diameter, equivalent diameter, surface area, sphericity, projected area and aspect ratio ranged from 0.35±0.08 to 0.60g±0.04g, 8.08±0.90 to 10.05±0.60mm, 4.04±0.53 to 5.00±0.10mm, 2.96±0.43 to 4.60±0.40mm, 4.52±0.45 to 6.03±0.20mm, 5.03±0.45 to 6.55±0.50mm, 4.75±0.42 to 6.03±0.41mm, 64.19±12.64 to 114.25±10.00mm2, 56±8.00 to 60±6.00%, 25.64±5.10 to 39.47 ± 3.80mm2, and 50±0.08 to 50±0.01mm respectively. The volume ranged from 0.35 ± 0.014 to 0.73 ± 0.014cm3, while the true and bulk densities ranged from 1.099 ± 0.141 to 1.110±0.424g/cm3 and 0.835±0.43 to 0.938±0.21g/cm3. Porosity decreased from 15.01±1.5 to 5.60±0.4% as moisture content increased from 10.50 to 20.10% (w.b). The angle of repose ranged from 39.80 to 60.10o with increase in moisture content. A set of prototype machines was developed to determine the parboiling time and temperature of the seeds and the terminal velocity of the hulls; as parboiling time ranged from 0 – 7.5minutes, the parboiling temperature ranged from 29 – 57.5oC and moisture content ranged from 10.50 – 20.10% (w.b). The optimum parboiling time, temperature and moisture content for hulling African breadfruit seeds were determined as 7.5minutes, 57.5oC and 20.10% (w.b) respectively. The experimental terminal velocity of the hulls ranged from 3.0±0.18 to 9.5±0.25m/s; the prototype blower however could not lift the seeds and kernels. Hence, the calculated values of the terminal velocity of the seeds and kernels ranged from 12.5 to 17.02m/s and 11.40 to 13.36m/s. Drag coefficient and drag force of the hulls ranged from 0.1 to 0.7 and 0.518×104 to 0.858 ×104N, whereas the drag coefficient and drag force of the seeds and kernels ranged from 0.09 to 0.2, 4.50 ×104 to 6.00×104N; 0.2 to 0.3 and 4.0×104 to 5.10×104N respectively.
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