Evaluation of Physico-Chemical Characteristics and Fattyacid Composition of Tiger Nut Oil (CYPERUS ESCULENTUS L.)

Abstract

Despite the fact that tiger nuts oil is not entirely new, it is still largely untapped in many parts of the world and underutilized even in areas where it is grown, especially in Nigeria. Therefore, the objective of this study is to evaluate the physicochemical properties and fatty acids composition of tiger nuts (Cyperus. esculentus) tuber oil. The oil was extracted from milled tiger nuts using the evaporation process with redistilled industrial grade n-hexane as solvent. The quality of the extracted oils was assessed in terms of acid value, iodine value, saponification value, peroxide value, refractive index, and unsaponifiable matter. Physiochemical properties of the oil samples were determined. The peroxide value, free fatty acid, and moisture content of tiger nut oils were monitored for four (4) weeks during the storage studies. The refractive index, specific gravity, acid value and free fatty acid value ranged between 1.46 - 1.47, 0.89 - 0.90, 0.4 - 1.40mg/g, and 0.20 - 0.75% respectively. The peroxide, saponification and iodine values ranged between 3.99- 4.43meq/kg, 183.25 -202.87 mg/kOH/g and 29.69- 31.74g/l2/g respectively. The major fatty acids (FAs) of the tiger nut oil were oleic (77.71%), palmitic (16.17%), and stearic (5.08%) acids for the black cultivar; oleic (64.12%), palmitic (11.86%), linoleic (11.87%) and dihum, linolenic (1.71%) for the brown cultivar while the yellow cultivar had oleic (68.89%), linoleic (12.77%), palmitic (13.33%) and stearic (4.46%). During storage, the oil's peroxide value, free fatty acid and moisture content was 5.62 mmol 20/kg, 1.54 mg KOH/g and 01338 respectively. These results indicate that tiger nut tuber oil could be a good source of edible oil, can replace imported olive, maize, sunflower and/or soy bean oils in foods and address domestic supply gaps of edible oils in Nigeria.