Evaluation of fatty acids and physicochemical characteristics of six varieties of bambara groundnut (Vigna subterranea L. Verdc) seed oils

A study was conducted to determine the suitability of six varieties of bambara groundnut (Vigna subterranea L. Verdc) seed oils, an under-utilized crop grown in Nasarawa State, Nigeria. For this purpose, fatty acid composition of six different seed colours of bambara groundnut was determined using standard analytical techniques. The most concentrated fatty acids were oleic acid (17.54-18.49%) < palmitic acid (21.79-23.27%) < linoleic acid (34.04-35.62%). Arachidic and behenic acids were present in small quantities with none of them recording up to 1.0% in any of the samples. Caprylic, palmitoleic, margaric, capric, lauric, myristic, arachidonic, erucic and lignoceric acids were all determined but not detected. Unsaturated fatty acids predominated in all the samples with an adequate amount of essential fatty acid (linoleic and linolenic acids). Significant differences were observed (p < 0.05) in the fatty acid compositions among the bambara groundnut dehulled seed cultivars. The results of physicochemical properties of bambara groundnut varieties seed oils showed mean range values of the following parameters: saponifications value (174.80-181.02 mg KOH/g); peroxide value (9.10-11.05 meqO2/kg); iodine value (111.98-122.22 mg of I/100g); acid value (1.28-1.40 mg KOH/g); specific gravity at 25 degrees C (0.874-0.881); unsaponifiable matter (2.39-2.47%); flash point (210-220 degrees C); kinetic viscosity at 40 degrees C (2.95-4.94). Generally, the values of the physicochemical parameters showed that the oils may be useful as edible oils due to their stability as frying oils and may also be useful industrially for the manufacture of products such as paints, liquid soaps and shampoos.