Abstract

Percentage oil yield and physicochemical properties of five different groundnut species (Valencia (Gargajiya), Virginia (Kampala Mubi and Michika) and Runner (Kwachamba brown and red) cultivated locally was determined. Results obtained showed that Gargajiya species yielded the highest amount of oil (37.80 ± 2.21%), closely followed by kampala michika (37.40 ± 3.20%) while kwachamba brown yielded the lowest percentage of oil (20.00 ± 2.06). The physicochemical properties of the groundnut oils showed that the crude kampala michika oil had significantly higher free fatty acid and acid values (3.95 ± 0.03% and 7.85 ± 0.28 mg/KOH/g) compare to the lowest value observed in crude kwachamba brown and kwachamba red (1.55 ± 0.03% and 3.09 ± 0.20 mg/KOH/g) respectively. The Saponification and iodine value were highest in crude and refined Gragajiya oil (220.20 ± 0.20 and 97.13 ± 1.56 g/100 g respectively). There was no significant difference at p < 0.05 in the refractive index of all the samples. Peroxide value was significantly higher at p < 0.05 in crude kwachamba brown (25.03 ± 0.07) compare to the lowest value observed in the same refined kwachamba brown oil (1.30 ±0.02 mg/kg). Thus suggesting that though Gargajiya and Kampala Mubi yielded highest, Kwachamba brown and kwachamba red are better for human consumption in terms of their physicochemical properties.

Key words: Groundnut, varieties, oil content, chemical and physical properties.