Abstract

The moisture-dependent physical properties are important to investigate for designing the post harvest equipments of the product .This study was carried out to determine the effect of moisture content on some physical properties. Four levels of moisture content ranging from 4-22% d.b (wet basis) and 4-22% d.b. for Darab and Goldasht, respectively was used. The average length, width, thickness, geometric mean diameter, equivalent diameter, arithmetic diameter, sphericity, thousand grain mass, angle of repose, grain volume, surface area and aspect ratio ranged from 7.52 to 7.89  mm, 3.95 to4.48 mm, 3.36 to 3.70 mm, 4.51 to 4.99 mm and 4.52 to5.00 mm, 4.89 to 5.36 mm, 60% to 63%, 32.2 to40.7 gr, 43º to 51º, 34.83 to 47.43 mm³, 57.28 to 70.38 mm², 52.57% to 56.74% as the moisture content increased from 4 to 22% d.b. for Darab and from 7.41 to 7.67 mm, 4.59 to 4.74 mm, 3.57 to 3.84 mm, 4.93 to 5.18 mm, 4.88 to 5.12 mm, 5.17 to 5.41 mm, 66.37% to 68.56%, 50.50 to 59.2 gr, 47° to 56°, 40.76 to 53.12 mm³, 62.27 to 72.38 mm², 64.22% to 62.95% with increase in moisture content from 4 to 22% d.b. for Goldasht. Goldasht has higher static angle of repose than Darab in all moisture content levels. As the moisture content increased, the bulk density was found to decrease from 547 to 520 kgm^-3 and from 640 to 601 kgm^-3 for Goldasht and Darab, respectively whereas true density and porosity were found to decrease from 1070 to 1010 kgm^-3 and 48.87% to 48.51% for Goldasht and from 940 to 850 kgm-3, 31.91% to 29.29% for Darab. The static coefficients of friction on various surfaces, namely, galvanized metal, plywood and plastic also increased linearly with an increase in moisture content. For galvanized metal and plastic Darab was higher correlated with moisture content than Goldasht.

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