Design, development, and performance evaluation of a portable chilli seed extractor based on crop-specific...

Manual extraction of chilli (Capsicum annuum L.) seeds is labour-intensive, time-consuming, and inefficient, often resulting in high seed damage and low recovery. This highlights the need for mechanized solutions that improve seed quality, operational efficiency, and productivity. This study aimed to design, develop, and evaluate a portable chilli seed extractor tailored to the physical, engineering, and mechanical properties of the local chilli variety KL1. Tri-axial pod dimensions at moisture contents of 85-86%, 64-65%, and 3-4% (wet basis) were 82.33 × 16.05 × 4.00 mm, 74.48 × 15.61 × 0.83 mm, and 78.34 × 22.73 × 0.43 mm, respectively, which guided the design of the hopper, shredding rollers, and reciprocating screen. The prototype incorporated a trapezoidal hopper, dual shredding rollers with spur gears, and a reciprocating separation unit. Performance evaluation under varying moisture levels, blade spacing, and screen amplitudes revealed a maximum extraction efficiency of 87.46% at 3-4% moisture content, 1.5 cm blade spacing, and 4 cm screen amplitude. Multi-response optimization using Design-Expert software identified optimum operating conditions yielding 76.21% extraction efficiency, 96.83% separation efficiency, 16.22 kg h^-1 throughput capacity, 3.10% mechanical seed damage, 90.66% germination, and a labour requirement of 3.8 min kg^-1. Economic analysis indicated a benefit-cost ratio of 1.31, a break-even point of 1.06 tonnes, and a payback period of 339 operational hours, reflecting an 89% reduction in extraction cost compared with manual methods. Overall, the developed chilli seed extractor offers a practical, cost-effective, and labour-saving solution for small-scale seed processing operations.