Moisture-Dependent Physical Properties of Grass Pea (Lathyrus sativus L.) Seeds

A. D. Zewdu , W. K. Solomon

Abstract


Knowledge on physical properties seeds and their dependence on moisture content is of
paramount importance in designing equipment for handling, storing and processing. In view of
this, the moisture dependence of some physical properties of grass pea (Lathyrus sativus L.)
seeds were studied at 8.5, 15.13, 21.43, and 30.66% moisture content (wet basis). The length,
width, thickness, geometric mean diameter, angle of repose and thousand grain mass increased
linearly from 5.02 to 5.34 mm, 4.88 to 5.01 mm, 4.22 to 4.50 mm, 4.70 to 4.94 mm, 26.33 to
31.73° and 82.0 to 114.56 g, respectively with increase in moisture content from 8.5 to 30.66%.
Sphericity and porosity increased from 93.53 to 94.17 % and 34.24 to 37.1 %, with increase in
moisture content from 8.5 to 15.13 % followed by a decrease from 94.17 to 92.46 % and 37.1 to
35.39 %, respectively when the moisture content increased from 15.13 to 30.66 %. The bulk and
true densities decreased linearly from 882.58 to 744.00 kg m-3 and 1343.51 to 1205 kg m-3,
respectively. The coefficient of static friction increased from 0.301 to 0.443, 0.353 to 0.521 and
0.222 to 0.515 for mild steel, plywood and glass surfaces, respectively with increase in moisture
content from 8.5 to 30.66 %. The coefficient of static friction was found to be highest for
plywood (0.521 at 30.66 %) among the surfaces considered.

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