Chemical Analyses of Groundnut (Arachis hypogaea) Oil

Abstract

Peanut (Arachis hypogaea L.) oil from seeds of six varieties; boro red, boro light, mokwa, ela, campala and guta as well as oil from three geographical zones in Nigeria; northern, eastern and western were investigated. Gas chromatography analysis showed high concentrations of oleic and linoleic acids in the oil samples. Capric (0.0%) and Lauric (8.1%) acids were absent and highest, respectively in the mokwa variety and hence diagnostic. More so, the comparative chemical analysis of peanut oil from the three zones and some selected refined vegetable oil; sunola, grand, olive and corn oil, indicated that western and grand oil had high iodine value 1.74±0.1 and 2.63±0.1, respectively, compared to others. The northern oil had high acid and fat value than the others (4.49 and 133%, respectively). Furthermore, the saponification value of the local vegetable oil was found to be significantly higher than the refined vegetable oil (P < 0.05), the eastern oil having the highest (140.25mgKOH/g). However, the peroxide values for both the local and refined oil were less than the standard peroxide value (10mEqKg^-1) for vegetable oil deterioration. Minerals were present and no rancidity was observed in all the samples. In conclusion, the groundnut oil from Nigeria may have a higher shelf life, and serve as a useful substitute in nutrition and industrial applications.