Improvement of the Dehulling Efficiency of Sorghum and Millet using Hydrothermal Treatments

  • EL Lazaro Department of Agricultural Engineering, Sokoine University of Agriculture, P.O. Box 3003, Morogoro, TANZANIA
  • JF Favier Department of Agriculture and Environmental Science, University of New Castle Upon Tyne, NE1 7RU, UNITED KINGDOM


Conditioning of grain with heat and moisture is known to loosen the adhesion of the seed coat from the endosperm and therefore improve the dehulling efficiency of some grains such as beans, cowpea and canola. This study investigated the effect of hydrothermal treatment on the improvement of dehulling efficiency of sorghum (Dionje and Jumbo varieties) and pearl millet (IM). Hydrothermal treatments investigated included, soaking the grain in distilled water, treating the grain with saturated steam for three different durations (5, 10, 15 minutes) followed by drying using either ambient air at 20oC, or heated air at 60oC. Abrasive dehulling of the pre-treated grain was accomplished using a Tangential Abrasive Dehulling Device (TADD). The effect of different hydrothermal treatments on the dehulling efficiency was evaluated based on the extent of seed coat removed and crude fibre reduction in the dehulled grain. Findings from this study showed that hydrothermal treatment of sorghum and millet improved the dehulling efficiency of Jumbo and Dionje sorghum varieties by an average of 10%, 7% respectively and pearl millet by 20% over unconditioned grain in terms of seed coat removal. In terms of crude fibre reduction in the dehulled grain, hydrothermal pre- treatments improved the dehulling efficiency by 14.5%, 27.3% for Jumbo and Dionje sorghum varieties respectively and by 13.7% for pearl millet over the unconditioned grain.
Journal of Agriculture, Science and Technology Vol.3(2) 2001: 15-30

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