Characterization of Oil Extracted from Two Varieties of Tiger Nut (Cyperus esculentus L.) Tubers

The qualitative determination of fatty acids from hexane extract of two varieties of Cyperus esculentus L. tuber oil using Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed the following fatty acids; palmitic acid, steric acid, Margaric acid, elaidic acid, oleic acid, erucic acid, behenic acid. and arachidic acid. For the Fourier Transform Infra-Red (FTIR) analysis, bands of 3469.09 cm -1 , 3463.3 cm -1 , sharp bands at 2867.28 cm -1 , 2037.86 cm -1 and 2866.32 cm -1 asymmetrical and symmetrical modes of vibration of –CH2-, strong band 1742.74 cm -1 and 1743.71 cm -1 due to ester carbonyl functional group of the triacylglycerols, bending vibrations of the CH2 and CH3 aliphatic groups, (C-CO-Oand O-CH2-C) and the inplanebending vibration of CH cis-olefinic groups seen at 1449.55 cm -1 , 1364 cm -1 and 1450.52 cm -1 , 1365.65, and 1450.52 cm -1 , 1365.65 cm -1 , vibration frequency at, 1166.97 cm -1 finger print of the stretching vibration of the C-O ester group, frequencies of the in-and out-of plane rocking of the cis-olefinic CH2 group at 718.51 cm -1 were observed for the brown and yellow tiger nut tubers oil respectively. The results were in favour of the utilization of the two varieties of Tiger nut (Cyperus esculentus L.) tubers oil in cosmetics, polymer and food industries.


Introduction
Tiger nut is an underutilized crop of the family Cyperaceae, which produces rhizomes from the base and tubers that are somewhat spherical. Pollination is by wind. Young tubers are white, while older tubers are covered by a yellow outer membrane; they are usually found within six inches of the ground surface. Vegetative colonies of its plants are often produced from the tubers and their rhizomes. The derivatives and benefits of Cyperus esculentus Lativum as a plant was reported [1]. It has many other names like; Chufa, Zulu nuts, yellow nut grass, and ground almond, edible rush and rush nuts [2]. In Nigeria, some of its native names include 'Aya' in Hausa, 'Imumu' in Yoruba, 'Ofio' or 'akihausa' in Igbo [3]. Oil is a One of the major source of essential mineral content in the diets of common people in Africa. Edible and Non-edible Oil Potentials of Tiger Nut (Cyperus esculentus) Grown in Nigeria was investigated [4]. Quality Characteristics of oil from two varieties of Cyperus esculentus L. tubers was physicochemical determined [5]. Despite its high nutritional value, tiger nut oil is hardly used in food industries compared to other vegetable oils such as olive and peanut oil. However, its benefits are increasingly being recognized, including its stability and similarity to olive oil in particular. Based on the available data, tiger nut oil has been established as an oil of good nutritional value which may be exploited to the great benefit of growers, processors and dealers of the tuber [6]. Evaluation of the physicochemical properties and fatty acids composition of tiger nut (Cyperus. esculentus) tuber oil in comparison with olive, maize, sunflower and soybean oils was reported. It showed that Tiger nut tuber oil can replace imported olive, maize, sunflower and / or soy bean oils in foods to face the high consumption of edible oils in Egypt [7]. Safety profile and antioxidant activity of fatty hydroxamic acid from underutilized seed oil of Cyperus esculentus was evaluated [8]. Physico-Chemical Characterization of Vegetable Oil and Defatted Meal from Two Varieties of Cyperus esculentus from Benin was reported [9]. This research is aimed at GC-MS and FT-IR analysis of oil from Brown and Yellow Cyperus esculentus tubers and justify their industrial potential for cosmetics, polymer and food preparations.

Sample Collection, Identification and Preparation
The dried tubers of the two varieties of Cyperus esculentus L. were crushed into powder using mortar and pestle and were stored in a plastic container prior to oil extraction.

Oil Extraction Procedure
The hexane extract was obtained by complete extraction using the Soxhlet extractor (GG-17, SHUNIU). The 50 g of each powdered sample was put into a porous thimble and placed in a Soxhlet extractor, using 150 cm3 of n-hexane (with boiling point of 40-60°C) as extracting solvent for 6 hours repeatedly until required quantity was obtained. The oil was obtained after evaporation using Water bath at 70°C to remove the excess solvent from the extracted oil. The oil was then stored in refrigerator prior to GC-MS analysis.

FT-IR Analysis
The analysis of the fatty acids in the Cyperusesculentus L. tuber oilsample was done at National Institute of Chemical Technology (NARICT), Zaria, Nigeria. Shimadzu 8400s Fourier Transformed Infra-red spectrophotometer was used.

GC-MS Analysis
The analysis of the fatty acids in the Cyperusesculentus L. tuber oilsample was done at National Institute of Chemical Technology (NARICT), Zaria, Nigeria, a Shimadzu QP2010 plus series gas chromatography coupled with Shimadzu QP 2010 plus mass spectroscopy detector (GCMS) system was used. The temperature programmed was set up from 70°C to 280°C. Helium gas was used as carrier gas. The injection volume was 2 µL with injection temperature of 250°C and a column flow of 1.80 mL/min for the GC. For the mass spectroscopy ACQ mode scanner with scan range of 30-700 amu at the speed of 1478 was used. The mass spectra were compared with the NIST 05 mass spectral library [10].

Discussion
The following major fatty acids were qualitatively identified form the GC-MS analysis; Palmitic acida natural saturated acid, present in plants, animals, and microorganisms [11]. It is among the fatty acids that isusedin high concentration in cosmetics [12]. Stearic acida saturated fatty acid with an 18-carbon chain and the IUPAC name octadecanoic acid was found, Stearic acid is mainly used in the production of detergents, soaps, and cosmetics such as shampoos and shaving cream products. Soaps are not made directly from stearic acid, but indirectly by saponification of triglycerides consisting of stearic acid esters. Esters of stearic acid with ethylene glycol, glycol stearate, and glycol distearate are used to produce a pearly effect in shampoos, soaps, and other cosmetic products. They are added to the product in molten form and allowed to crystallize under controlled conditions. Detergents are obtained from amides and quaternary alkylammonium derivatives of stearic acid. Surfactants, cosmetics and personal hygiene products are in fact prospects of stearic acid [13]. Heptadecanoic acid or margaric acid is a saturated fatty acid was also detected. Oleic Acid's presence makes it a great moisturizer, and a number of cosmetic companies add it to lotions and soaps in order to boost their ability to nourish the skin [14] Behenic acid detected is often used to give hair conditioners and moisturizers their smoothing properties. Also used as antifoam in the manufacturing of detergents [15]. Arachidic acid also called eicosanoic acid is a saturated fatty acid was detected. It is found in appreciable quantities only in some vegetable fats and oils where it occurs as glycerol ester [16]. Erucic acid was also found, products produced using erucic acid include cosmetics [17].
The FT-IR bands of 3469.09 cm -1 , 3463.3 cm -1 observed in yellow and brown tiger nut oil respectively are the region of unsaturated fatty acid. The asymmetrical and symmetrical modes of vibration of -CH 2 -exhibit very strong and sharp bands at 2867.28 cm -1 , 2037.86 cm -1 and 2866.32 cm -1 for yellow and brown tiger nut oil. The band at 1742.74 cm -1 and 1743.71 cm -1 is very strong and sharp band due to ester carbonyl functional group of the triglycerides i.e C=O stretching vibrations no absorption around 1710 cm -1 this shows that the fatty acids is exclusively in ester forms. [18]. The bending vibrations of the CH 2 and CH 3 aliphatic groups,(C-CO-O-and O-CH 2 -C) and the in-plane bending vibration of CH cis-olefinic groups are seen at 1449.5 5 cm -1 , 1364 cm -1 and 1450.52 cm -1 , 1365.65 cm -1 for yellow and brown tiger nut oil respectively. The vibration frequency at, 1166.97 cm -1 for brown tiger nut oil and yellow tiger nut oil is finger print of the stretching vibration of the C-O ester group. The frequencies of the in-and out-of plane rocking of the cis-olefinic CH 2 group are at 718.51 cm -1 for the brown and yellow tiger nut. The observed differences in frequency positions of the ester carbonyl, and the inactivity or absence of some in-plane bending are attributed to the variation in fatty acids composition, chain length, degree and position of double bonds in the triacylglycerols [19]. However, polymeric applications of quality characterized plants oils in general found useful in polymer preparations. A plant oil with a metathesis catalyst produces cyclohexadiene (CHD), which can then be converted to other monomers through isomerization or polymerized to mimic petroleum-based polymers. The preparation of cyclohexadiene (CHD) can be performed with little to no plant oil purification, minimal catalyst loading, no organic solvents, and simple product recovery by distillation. These monomers can be used to supplement or substitute petroleum-based monomers traditionally used in the preparation of polymeric materials [20].

Conclusion
The results of FT-IR and fatty acid composition of oil from two varieties of tiger nut (Cyperus esculentus L.) tubers through GC-MS analysis indicated that there is no different as such in the two varieties and they are suitable for industrial production of cosmetic and polymeric products.