This study presents the design and evaluation of a low-cost, manually operated hydraulic press for extracting oil from Kalahari melon seeds in rural Namibia. Traditional firewood-based extraction methods are labor-intensive, inefficient, and pose health and environmental risks. Guided by contextual engineering principles, the manual hydraulic press was co-designed with local women and fabricated from low-cost, readily available scrap materials sourced from rural markets. Experimental trials were conducted in triplicate (n = 3 per treatment) to evaluate four seed pre-treatment conditions, (1) roasted and crushed, (2) unroasted and crushed, (3) roasted and uncrushed, and (4) untreated, and two pressing chamber diameters (5.08 cm and 7.63 cm). The manual hydraulic press reduced processing time from approximately 5–8 h to less than 5 min per batch and increased oil yield from reported traditional values of 5–7% to 8.5–9.5% by mass. Participants reported improved oil clarity, reduced physical strain, and enhanced usability during field testing. While long-term scalability and social or environmental impacts were not directly assessed, the results demonstrate community-scale technical performance and short-term user acceptance of a firewood-free oil extraction technology. Findings are discussed in relation to gendered labor demands and clean-energy processing in off-grid contexts, without implying direct measurement of Sustainable Development Goal outcomes.
Kandume et al. (Sun,) studied this question.