Design, Fabrication, and Performance Evaluation of a Turmeric Polishing Machine for Smallholder Farming Applications

• Diesel engine operated turmeric polishing machine was developed. • Polishing capacity is raised to 360 kg/hr efficiently compared to SS engine operated polishers • Operating speed is increased to 85 rpm at 20min and 9% MC for polishing • Attained higher polishing efficiencies compared to other same technologies developed • The Polisher machine is suitable for smallholder farmer and small-scale enterprises was developed. Turmeric polishing in Ethiopia is predominantly performed manually, leading to high labor demand, low efficiency, and inconsistent product quality. This study aimed to design, develop, and evaluate a small-scale mechanical turmeric polishing machine suited to the needs of smallholder farmers. A turmeric polishing machine featuring an octagonal drum driven by a 5 HP diesel engine was designed, fabricated, and tested. Its performance was evaluated using a randomized complete block design (RCBD) and regression analysis at three drum speeds (70, 85, and 95 rpm), polishing durations (15, 20, and 25 min), and moisture contents (6%, 9%, and 11% wb). The parameters assessed included polishing efficiency, throughput capacity, product damage, and fuel consumption. Statistical analysis depicted that increases in drum speed and moisture content were directly associated with higher product damage and fuel consumption. The maximum polishing efficiency of 95% was achieved at 85 rpm, 25 min polishing time, and 11% (wb) moisture content, corresponding to a throughput capacity of 364 kgh⁻¹ with higher damage. Optimal performance, balancing polishing quality and minimal damage, was observed at 85 rpm, 20 min, and 9% (wb) moisture content. The developed turmeric polishing machine substantially enhances post-harvest handling efficiency, product uniformity, and labor productivity. The results confirm that the technology is technically feasible, economically viable, and well-suited for adoption by smallholder farmers to improve turmeric processing and value addition.