Effect of moisture content on some physical properties of HQPM 5 quality protein maize (Zea mays)

Abstract

This study on HQPM 5 quality protein maize was performed to investigate the effect of moisture content on the selected physical properties, as the knowledge about the physical properties of this grain is important for designing processing machineries. For this purpose, moisture content of grains was varied from 9% to 25%, wet basis (wb). In this study moisture content range, the average length, width, thickness, surface area, volume, geometric mean diameter and arithmetic mean diameter of quality protein maize grains increased significantly (PË‚0.01) from 9.2476 to 10.2033 mm, 7.8684 to 8.2641 mm, 3.8572 to 4.7139 mm, 138.433 to 158.0703 mm2, 107.40 to 138.83 mm3, 6.6445 to 7.0822 mm and 7.1304 to 7.5485 mm respectively, with increase of moisture content. A nonlinear significant increase of grain sphericity from 68.7438 to 76.2248 was observed in the studied moisture range. Thousand grain weight, true density, porosity and angle of repose increased linearly (P<0.01) from 223 to 253 g, 1110 to 1290 kg/m3, 22.2087 to 34.4594 and 24o to 37.03o, whereas bulk density decreased linearly (P<0.01) from 982.4 to 812 kg/m3. In the considered range of moisture content, all of these physical properties exhibited moisture dependence according to linear relationships except the sphericity.