Effects of Threshing Machine-Crop Parameters on Milling Quality of Rice

Authors

  • Solomon Tekeste Hailemesikel Bahir Dar University, Bahir Dar Institute of Technology, Faculty of Mechanical and Industrial Engineering, Bahir Dar Ethiopia https://orcid.org/0000-0003-0047-7952
  • Mersha Alebachew Ethiopian Institute of Agricultural Research, Fogera National Rice Research and Training Center, Woreta Ethiopia
  • Mulugeta Admasu Delele Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Germany https://orcid.org/0000-0002-5869-2009
  • Addisu Negash Ali Bahir Dar University, Bahir Dar Institute of Technology, Faculty of Mechanical and Industrial Engineering, Bahir Dar Ethiopia https://orcid.org/0000-0002-7380-6780
  • Solomon Workneh Fanta Bahir Dar University, Bahir Dar Institute of Technology, Faculty of Chemical and Food Engineering, Bahir Dar Ethiopia https://orcid.org/0000-0002-0244-1104
  • Geta Kidanemariam Bahir Dar University, Bahir Dar Institute of Technology, Faculty of Mechanical and Industrial Engineering, Bahir Dar Ethiopia

Abstract

High Post-harvest losses are a major challenge for rice production in sub-Saharan Africa. Threshing grain damage is one of the crucial factors affecting the quality and quantity losses of rice. This study investigated the effects of grain moisture content (MC), drum peripheral speed (DS), and spike arrangement (SS) on head rice yield (HRY) for three locally grown rice varieties (VAR), taking into consideration the initial condition of the grain. Experiments were conducted using a factorial design with four factors, and three replications. The results indicated that all the main effects (VAR, MC, DS, SS) and some of the interaction effects of the independent variables significantly impacted HRY and milling breakage. Ediget variety had higher HRY and lower milling breakage, whereas Nerica-4 had lower HRY and higher milling breakage compared to the other two varieties. As MC increased from 11.44% to 24.01%, the least square mean HRY increased from 42.5% to 62.4% and milling breakage decreased from 21.9% to 6.8%, respectively. An increase in drum peripheral speed resulted in a decrease in HRY and an increase in milling breakage. Decreasing the spike spacing resulted in lower HRY and higher milling breakage. The harvest moisture content was identified as the most critical factor affecting HRY and milling breakage followed by drum peripheral speed and spike spacing. The results of this study can be used to develop effective strategies to minimize rice grain damage during mechanical threshing so as to improve milling quality.

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Published

2025-12-31

Issue

Vol. 27 No. 4 (2025): CIGR Journal

Section

VI-Postharvest Technology and Process Engineering