Moisture dependent physical and mechanical properties of organic beans (Phaseolus vulgaris L.)

Abstract

The physical and mechanical properties of organic bean grains (Phaseolus vulgaris L.) were determined as a function of moisture content in the range of 16.14-29.03% dry basis (d.b.). The average length, width and thickness were 17.55, 9.75 and 5.83 mm, at a moisture content of 16.14% d.b., respectively. Nonetheless, the thousand grain mass increased from 643 to 730 g, the projected area from 148.81 to 184.71 mm(2), the true density from 1110 to 1285 kg m(-3), the porosity from 36.89% to 48.79% and the terminal velocity from 6.25 to 7.45 m s(-1) in the moisture range from 16.14% to 29.03% d.b. The static coefficient of friction of organic bean grains increased the linearly against surfaces of six structural materials, namely, rubber (0.43-0.49), stainless steel (0.30-0.34), aluminium (0.42-0.45), galvanized iron (0.32-0.35), MDF (medium density fibreboard) (0.29-0.33) and glass (0.29-0.32) as the moisture content increased from 16.14% to 29.03% d.b. The shelling resistance of organic bean grains decreased from 180 to 145 N as the moisture content increased.