evaluation of physical, mechanical and nutritional properties of sesame seed (sesamum indicum l.) in different moisture contents for the optimization of the processing operation

in this study, moisture dependent physical, mechanical and nutritional properties of sesame seed were evaluated. in the moisture range of 4.54–19.27% (d.b.), seed length, width, thickness, arithmetic mean diameter and geometric mean diameter increased linearly from 2.93 to 3.01 mm, 1.74 to 1.78 mm, 0.78 to 0.86 mm, 1.81 to 1.88 mm and 1.58 to 1.66 mm respectively with increase in moisture content. the sphericity, surface area, one thousand seed mass, true density and porosity increased from 54.04 to 55.25%, 6.68 to 7.35 mm2, 2.43 to 2.75 g, 1207 to 1236.8 kg/m3 and 51.03 to 53.12%, respectively, while bulk density decreased from 591 to 579.5 kg/m3. the terminal velocity and angle of repose increased from 4.95 to 5.4 m/s and 31.5 to 32.8º, respectively. the highest static coefficient of friction was found on the plywood surface. the static coefficient of friction increased from 0.54 to 0.56, 0.50 to 0.54 and 0.41 to 0.45 for plywood, steel and galvanized iron sheet, respectively. the results of mechanical test showed that the force required for initiating seed rupture decreased from 25.66 to 18.36 n and 27.56 to 21.20 n, and the energy absorbed at seed rupture increased from 15.52 to 18.08 mj and 15.84 to 18.33 mj, with increase in moisture content from 4.54% to 19.27% d.b., for vertical and horizontal orientations, respectively. sesame seeds contained high amounts of oil (46.57%), crude protein (23.75%) and calcium (0.98%). the mineral contents of the seed for phosphorus, potassium, magnesium and iron were 508.3, 486.7, 288.2 and 10.7 mg/100g of dry matter, respectively. the major fatty acids were oleic acid (43.4%), followed by linoleic acid (36.3%), palmitic acid (11.75%) and stearic acid (6.25%).