Physicochemical Analysis of Locally Produced Groundnut Oil from Selected Processing Units in Zamfara State

Groundnut oil is the most widely consumed edible oil in the North West geopolitical zone of Nigeria, where Zamfara State is a significant groundnut-producing area. The quality of locally produced groundnut oil is variable and subject to adulteration, yet systematic quality surveillance data from the state are limited. This study conducts physicochemical analysis of groundnut oil samples from 30 small-scale processors and 15 market vendors in Gusau, Talata Mafara, and Kaura Namoda. Quality parameters evaluated include free fatty acid content, peroxide value, iodine value, refractive index, specific gravity, moisture content, unsaponifiable matter, and colour using the AOCS and AOAC standard methods. Results showed that 40 percent of processor samples and 60 percent of vendor samples exceeded the acceptable free fatty acid content of 2 percent, indicating early rancidity development. Peroxide values were above the Codex Alimentarius limit in 33 percent of vendor samples. The study draws on recent literature on edible oil quality surveillance in the informal food sector in Nigeria. The findings highlight the need for quality monitoring, capacity building on post-extraction handling, and cold storage access for groundnut oil producers in Zamfara State. Recommendations are provided for the Zamfara State Ministry of Agriculture, the Standards Organisation of Nigeria, and the National Agency for Food and Drug Administration and Control. Keywords: groundnut oil, physicochemical properties, free fatty acid, rancidity, Zamfara State