Determination of physical properties of soybean, design and fabrication of improved soybean dehuller

Abstract

The objective of this study was to investigate the methods for improving dehulling efficiency and throughput of soybean dehuller, which included studying of some physical properties of soybean at different moisture levels related to dehulling, the use of different pre-treatment methods to loosen the seed coat to facilitate its removal during dehulling, and finally to develop an improved manually operated prototype dehuller which can dehul moist grain without clogging and undertake performance test of this dehuller. Four levels of moisture content ranging from 14 to 20 % dry basis (d.b) were used to evaluate the effect of moisture content on physical properties of soybean grains. In this moisture range, mean grain length, width, thickness, arithmetic mean diameter, geometric mean diameter, surface area, porosity and thousand grains weight increased with increasing moisture content. On the other hand, bulk density, true density and sphericity were found to decrease with increase in moisture content. The prototype dehuller was designed and fabricated with a dehulling surface which can dehul moist grain without clogging. The effect of pre-treatment methods on dehulling was carried out to evaluate the dehulling efficiency and throughput of the prototype dehuller. The pre-treatments investigated included boiling the grain at different durations followed by cooling to room temperature and soaking the grain for different durations followed by a rest period to allow surface moisture to be absorbed. The improved dehuller was used to dehull the pre-treated grain and the effect of pre-treatments on dehulling efficiency was evaluated based on the extent of seed coat removal. Also the effect of different pre-treatments on throughput of the dehuller was evaluated. The dehuller was able to achieve dehulling efficiency of 70.62 % for Uyole Soya-1 and 72.57 % for TGX 1895-33F. Throughput obtained was 50.76 kg/h and 55.50 kg/h for Uyole and TGX 1895-33F, respectively.