EFFECT OF MOISTURE CONTENT ON SOME PHYSICAL AND FRICTIONAL PROPERTIES OF AFRICAN LOCUST BEAN (PAKIA BIGLOBOSA)

Abstract

The moisture-dependent handling properties (linear dimensions, sphericity, bulk and true densities,
porosity) and flow or frictional properties (angle of repose and static coefficient of friction) were
investigated for African Locust Bean (Pakia biglobosa) at moisture contents in the range of 7.45% to
15.2% (d.b.). All the seed dimensions showed a linear response to an increase in moisture content within
the range of moisture content studied. All other measured parameters increased polynomially with
increased in moisture content. They are: seed equivalent diameter (11.02 to 12.73mm); seed volume
(362.74mm³ to 542.01mm³); seed surface area (308.50mm² to 406.66mm²); bulk density and true density
(0.45g/cm³ to 0.54g/cm³ and 0.80g/cm³ to 1.40g/cm³ respectively); aspect ratio, sphericity and porosity
(0.76 to 0.79, 0.71 to 0.70 and 0.41 to 0.61 respectively); angle of repose (21.05^o to 37.45^o); while static
coefficient of friction increased for all surfaces from 0.53 to 0.92 for plywood, 0.45 to 0.84 for mild steel
and 0.36 to 0.71 for aluminum with plywood giving the highest range of values. The data obtained from
this study is useful in the structural design of hoppers, bins and silos for storing the seeds and the
equipment for processing, sorting, sizing and other post-harvest operations.