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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/3997

Title: Effect of rewetting and drying on selected physical properties of Asontem Cowpea Variety
Authors: Ampah, Jonathan
Issue Date: 19-Jun-2011
Abstract: This study assessed the effect of rewetting and drying on some selected physical properties of asontem cowpea at eight selected moisture contents namely, 8.07, 11.45, 17.20 and 22.54% w.b. for rewetting; and 9.58, 11.50, 15.13 and 19.00% w.b. for drying. The length, width, thickness, geometric mean diameter, surface area, volume, 1000 grain mass, bulk density, true density, porosity, filling angle of repose and the static coefficient of friction increased with increasing moisture content during rewetting. In the moisture content range of 8.07% w.b. to 22.54% w.b., the length, width and thickness increased non-linearly from 7.00 to 7.29mm, 6.27 to 6.33mm and 4.54 to 4.69mm respectively. The geometric mean diameter, surface area, volume and 1000 grain mass increased from 5.83 to 5.99mm, 107.03 to 113.09mm2, 104.45 to 113.45mm3 and 120.15 to 130.58g respectively; while bulk density and true density decreased non-linearly from 752.95 to 682.93kg/m3 and 1219.90 to 1161.39 kg/m3. Porosity increased linearly from 38.13% to 41.16%. The filling angle of repose increased non-linearly from 27.81 to 32.31; whiles the coefficient of static friction also increased non-linearly from 0.29 to 0.41, 0.30 to 0.45 and 0.25 to 0.32 for plywood, mild steel and rubber respectively. Sphericity decreased from 83.7% to 82.6% with increasing moisture content. The result obtained for drying showed that with decreasing moisture content, length, width and thickness dimensions as well as 1000 grain mass and filling angle of repose decreased from 8.16mm to 7.11, 6.36mm to 6.28, 4.77mm to 4.61, 132.85g to 120.93g and 29.350 to 27.920 respectively. The geometric mean diameter, surface area and volume decreased from 5.89 to 6.27mm, 109.46 to 123.87mm2, and 108.02 to 130.23mm3respectively; while bulk density and true density increased non-linearly from 710.93 to 663.12kg/m3 and 1185.92 to 1063.80 kg/m3; porosity increased non-linearly from 37.55 to 39.98%. However, the values of static coefficient of friction for plywood, mild steel and rubber appeared to increase in the moisture content range of 11.50 and 15.13% wb and then decreased at 19.00% wb. The overall result of this study shows that linear dimensions increased non-linearly with increasing moisture content during rewetting and decreased with decreasing moisture content during drying. The filling angle of repose and the coefficient of static friction also increased non-linearly with increasing moisture content. Plywood offered the highest coefficient of friction during drying followed by mild steel and rubber. However, for rewetting, mild steel offered the highest coefficient of friction followed closely by plywood then rubber.
Description: A Thesis submitted to the Department of Agricultural Engineering, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science in Food and Postharvest Engineering, 2011
URI: http://hdl.handle.net/123456789/3997
Appears in Collections:College of Engineering

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