Design and Performance Testing of a Foot-Operated Groundnut Oil Expeller for Rural Women Processors in Zamfara State

Groundnut oil extraction through traditional manual pounding and boiling methods is associated with low yields, excessive labour, and poor oil quality in rural communities across North West Nigeria. This project presents the design and performance evaluation of a foot-operated groundnut oil expeller prototype developed for use by women processors in Zamfara State, where access to electric power and motorised equipment is limited. The expeller mechanism uses a lever-amplified foot pedal to drive a reciprocating ram that presses roasted groundnut paste through a perforated barrel, allowing oil to drain into a collection vessel. Design parameters including pressing force, barrel dimensions, and lever geometry were computed based on the oil content of local groundnut varieties and target throughput requirements. A prototype was fabricated from mild steel and tested with samples of roasted Samnut 24 variety groundnuts under controlled conditions. Extraction efficiency, oil yield per kilogram, pressing cycle time, and operator fatigue were evaluated over repeated experimental sessions. The expeller achieved an oil yield of 38 percent by weight of processed groundnuts, exceeding the 28 percent average reported for traditional hand pressing methods. Operator fatigue assessment using perceived exertion ratings confirmed the design was sustainable for two-hour continuous operation sessions. Fabrication cost was 29,600 naira. The study recommends dissemination of the design through women cooperative networks in rural Zamfara. Keywords: groundnut oil expeller, foot-operated press, rural food processing, Zamfara State, women processors.