Effect of moisture on physical properties of dekoko

Abstract

Abstract: Dekoko is a cool season legume plant grown in northern Africa.  It is a rich source of protein for people in the region.  The effect of moisture on some of the physical properties of dekoko seed was studied because it frequently affects some important parameters for the design of mechanical unit operations.  The moisture content of dekoko seed was determined according to ASAE standards S352.3 and all other physical properties following standard procedure described elsewhere.  The length, width, thickness, geometric mean diameter, thousand seed mass, porosity, true density and angle of repose increased from 5.60 to 6.51 mm, 4.99 to 5.78 mm, 4.60 to 5.44 mm, 5.05 to 5.89 mm, 94.08 to 126.10 g, 39.36 to 48.14%, 1361.66 to 1470.77 kg/m³ and 29.89° to 37.84° respectively.  The sphericity increased from 90.05% to 91.14% with increase in moisture content from 10.28% to 19.67% and decreased from 90.83% to 90.55% with further increase of moisture content from 24.42% to 28.61%.  Whereas, bulk density decreased from 829.89 kg/m³ at 10.28% to 762.75 kg/m³ at 28.61% moisture content.  In the same moisture range, the lowest value of static coefficient of friction recorded when dekoko seed slide against mild steel (0.35 to 0.48,) and the highest value of static coefficient of friction noticed when dekoko seed slide against plywood (0.42 to 0.54).  The static coefficient of friction of for galvanized iron increased from (0.37 to 0.51) as moisture increased from 10.28% to 28.61%.  Generally, moisture content directly or indirectly affected the physical properties of dekoko seeds.

Keywords: dekoko seed, moisture content, static coefficient of friction, true density, angle of repose