The Moisture Content Effect on Some Physical and Mechanical Properties of Corn (Sc 704)

Abstract

Physical and mechanical properties of grains are necessary for designing the facility of storage, handling and processing of agricultural products. Physical and mechanical properties of corn grains were determined as a function of moisture content in the range of 4.73-22% w.b. (wet basis) using standard techniques. The average length, width, thickness, geometric mean diameter, equivalent diameter, arithmetic diameter, sphericity, grain volume, surface area and aspect ratio ranged from 11.62 to 12.60 mm, 7.27 to 7.98 mm, 4.47 to 4.71 mm, 7.20 to 7.77 mm and 7.63 to 7.96 mm, 7.77 to 8.43 mm, 62.31% to 62.00%, 209.66 to 265.00 mm 3 , 137.69 to 160.09 mm 2 and 63.05% to 63.77% as the moisture content changed from 4.73-22% w.b. With increase in moisture content, the bulk density was found to decrease from 710 to 649 kgm -3 whereas true density and porosity increased from 1250 to 1325 kgm -3 and 43.2% to 51.02%. In the moisture range from 4.73% to 22% w.b., studies on rewetted corn grains showed that the thousand grain weight (TGW) increased linearly from 271.0 to 321.4 g. The static coefficient of friction of corn grains increased linearly against surfaces of three materials, namely, plastic (0.32–0.51), plywood (0.48–0.60) and galvanized iron (0.38–0.65) and the static angle of repose increased from 49º to 58º when the moisture content increased from 4.73% to 22% w.b. The mechanical properties of corn were determined in terms of average rupture force and rupture energy. Rupture energy of corn grains generally increased in magnitude with an increase in moisture content, while rupture force decreased for compression.