Original Article Evaluation of Fatty Acids in Libyan olive oils by Gas Liquid Chromatography

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1 Available online at International Journal of Chromatographic Science Universal Research Publications. All rights reserved Original Article Evaluation of Fatty Acids in Libyan olive oils by Gas Liquid Chromatography Abdulsalam A. Benkhayal, Nabil R. Bader, Khaled M. Elsherif *, Rajab El-kailany, Salah Elmgsbi Faculty of Science, University,, Libya Raslanouf oil company (RASCO), Libya Tel: 0000 Received February 0; accepted March 0 Abstract Olive oil samples were collected from eighteen different sites to represents most olive oil farms producers in Libya (North Africa). The samples were separated by liquid-liquid extraction and the analysis of main fatty acids of the oil: palmitic (C:0), palmitoleic (C:), stearic (C:0), oleic (C:), and linoleic (C:) was performed by Gas chromatography technique. The acidity, saponification value, and UV absorbance at wavelengths and 0 nm were also measured for quality control of olive oil. The oleic acid level in all oil samples (except Ekaam Valley) was found within the normal values ( %). The most Libyan olive oil samples have a good quality and considered as extra virgin grade oil. 0 Universal Research Publications. All rights reserved Keywords: Olive oil, Fatty acid, Gas Chromatography, Libya. Introduction Olive oil is one of the oldest known vegetable oils mainly produced in the countries surrounding the Mediterranean Sea. It is a natural fruit juice, obtained from the fruit of the tree Olea europea, with a unique composition and quality []. The importance of virgin olive oil is related to its high levels of monounsaturated fatty acids (mainly oleic acid), and several antioxidants. Oil with higher monounsaturated fatty acids (MUFAs) and lower saturated fatty acids (SFAs) are preferred because of the proven beneficial effect of MUFAs on serum cholesterol levels []. Nowadays, it is well known that the health effects of dietary MUFA were essentially attributed to decreased endothelial activation, and LDL susceptibility to oxidation []. Although the high level of unsaturation of fatty acids contained in oils of plant origin is appreciated by nutritionists, it causes several technological problems, because of their greater susceptibility to oxidation. Oxidation of the fats degrades the organoleptic quality of food, reduces its nutritional value, and products of the oxidation processes can participate in the aging of an organism and in the aetiology of cardiovascular diseases and cancer []. MUFA are fatty acids with a single double bond in the molecule. The most abundant MUFA in the diet is oleic acid (C:n ) []. Fatty acid composition has been shown to influence the stability of oils, and polyunsaturated fatty acids have been found to contribute to the rancidification of several oils []. The main fatty acids in olive oil are those comprised between the myristic ( carbon atoms) and lignoceric ( carbon atoms). The most prominent are the monounsaturated oleic and palmitoleic, and the polyunsaturated linoleic and linolenic []. Finally, fatty acid composition has been found to be responsible for the odors and flavors associated with oil quality []. Nevertheless, the concentrations of these compounds in VOO are strongly affected by agronomical and technological factors, such as olive cultivar, place of cultivar, climate, and degree of maturation, crop season and production process []. The unsaturated olive oil fat in the diet is linked with reduces in the risk of coronary heart disease. Unlike saturated fat, olive oil lowers total cholesterol and LDL levels in the blood. It is known to lower blood sugar and blood pressure. This is because olive oil contains high monounsaturated fatty acid; oleic acid [, ]. Fatty acid composition has been shown to influence the stability of oils, and polyunsaturated fatty acids have been found to contribute to the rancidification of several oils []. Fatty acid composition has been found to be responsible for the odors and flavors associated with oil quality. Some studies have been carried out with the aim of characterizing particular productions of olive oil, which have given great importance to the fatty acid profile. The Italian production was investigated and characterized by Panelli et.al has measured the fatty acid composition of virgin olive oils from Pula (Croatia),the fatty acid profile evolution of oils produced by typical Spanish olive cultivars like Picual and Hoijblanca and Moroccan Picholine has also been studied [].. Level of the fatty acids in olive oil Table, shows the amounts of fatty acids in the virgin olive oils, refined olive oil and olive pomace oil. Palmitic and oleic acids were considered as major fatty acids while palmitoleic,stearic,linolenicand linoleic acids contents were International Journal of Chromatographic Science 0; (): -

2 Table :- % Fatty Acid in the Olive Oil Olive-Pomace Oils % Refined Olive Oils % * CAN Carbon atoms number Table. The Code and Sample Site for Study Samples Sample code Longitude Nu 0 00 Aj 0 00 Bg 0 Az 0 Gr 0 00 Tj 0 An 00 Th 00 Ts 00 Bw 00 Mi Gm 0 00 Ek 00 Kh Zl 00 Aw 00 Gr 00 Bn Virgin Olive Oils % Sample site Alnowahi-- CAN * C: C: C:0 C:0 C: C:0 C: C:0 C: C: C0:0 C0: C:0 C:0 International Journal of Chromatographic Science 0; (): - Fatty Acid Trans Linoleic acid Trans Linolenic acid Myristic Palmitic acid Palmitoleic acid Heptadecanic Heptadecenic Stearic acid Oleic acid Linoleic acid Arachidic acid Gadoleic acid Behenic acid Lignoceric acid Sample number 0 Table - Chromatographic method for the analysis of fatty acid methyl esters Chromatographic system TECHCOMP GC-00 Detector FID Column Fused-silica capillary column (0 m 0.µm i.d.. µm film thickness, (J&W scientific). Oven temperature o C (min)-00c(min) at 0 o C /min -0 o C (min) at o C /min -0 ( min) at. o C /min. Carrier gas Helium Injection volume µl Inlet temperature 00 o C Detector temperature 0 o C Inlet Split / spitless Split ratio (:00) low [0].. Materials and Methods. Oil Samples Table illustrates the code and sample area of the studied samples. For geographical classification, samples were arranged from west to east region from to, during March 0.. Determination of Acid Value The acid value was determined by directly titrating the oil / fat in an alcoholic medium against standard potassium hydroxide solution. Acid value = VN. W

3 Where: V = Volume in ml of standard potassium hydroxide, N = Normality of the potassium hydroxide solution, W = Weight in g of the sample. Determination of Saponification Value Saponification Value was determined by the following formula: Where: A = ml HCl, for blank B = ml HCl for sample W = weight of sample g (dry basis) N= normality of H SO solution. = equivalent weight of potassium hydroxide. UV Spectrophotometric Investigation Absorbance at and 0 nm was determined using UV- VIS spectrophotometer (UV Aquarius - 0 UV-Visible Spectrophotometer, Japan). The purity of olive oil can be determined from three parameters []: K Absorbance at nm K0 Absorbance at 0 nm ΔK ΔK = K0 K K. Fatty Acid Composition The fatty acid composition of the oils was determined by gas chromatography (GC) as fatty acid methyl esters (FAMEs) according to the methods described in regulation of EEC /. Methyl esters are formed by transesterification with methanolic potassium hydroxide as an intermediate stage before saponification takes place.. Analysis of Fatty Acids Analysis of fatty acids was carried out by gas liquid chromatography (GLC), using (TECHCOMP gas chromatography GC-00) equipped with flame ionization detector (FID) under the following conditions:. Results and Discussion Quality parameters; acidity, saponification number, UV spectrophotometric Indices, of olive oils from the samples under study are shown in Table. Table - Quality Parameters of Libyan Olive Oils Samples No. Sample site Acidity % Saponification value (mg/g) Abs. nm Abs. 0 nm ΔK Alnowahi As shown in Table, the maximum value of acidity was in "" (.0 %), while " (Spanish olive trees)" had the lowest free acidity (0. %). The saponification number lied between (.-0. mg/g KOH). The absorbance measurements at and 0 nm did not exceed the limit of.0 and 0.. Kenan Tanılgan et al reported the physical, chemical properties of five Turkish Olive Oils contained to have a free acidity (as Oleic acid %) value range from %. and a saponification number range from.-0. mg KOH/g []. Manel Issaoui el al (00), reported that the K values of virgin olive oils from four Tunisian cultivars (north and south Tunisia) range from. -. and K0 value were International Journal of Chromatographic Science 0; (): -

4 around 0. []. The composition of fatty acids that obtained by gas chromatography analysis are listed in Table. The highest value of Oleic acid content was in sample (. %). However the lowest Oleic acid content was recorded for Kaama sample (. %). Palmitic acid content was the highest in Beerl-ghanam sample (0. %). The highest value of Linoleic acid content was in sample (. %). While sample was the highest in Stearic acid value (. %). Samia Dabbou et al reported the fatty acids content of Tunisian olive oils, Palimtic acid is within the range of.-. %, Stearic acid from.-. %, Oleic acid Table - Fatty acid composition of Libyan olive oil samples Linoleic Acid Seatric Acid Oliec Acid (C:) % (C:0) % (C:)% Figure Dendrogram of the normalized data of fatty acid composition of Libyan Olive Oil from.-. %, and Linoleic acid from 0.-. % []. The resulting dendrogram of fatty acid composition is shown in Figure revealed three major groups. The first group includes seven varieties:,,,,, Beerl-ghanam, and shows medium level of oleic acid (0 % - %). And the second group includes seven varieties:,,,, Alnowahi--,, and have high levels of oleic acid (0 % - %). The third group includes four varieties:,,, and have low level of oleic acid ( % - %), and high level of linoleic acid. Palmitic Acid (C:0) % Conclusion This study allowed us to depict eighteen Libyan olive oils. The results of physicochemical Properties of this study demonstrated that the studied Libyan olive oil samples produce extra virgin olive oils. It is concluded from the obtained results that olive oil acidity lies between ( %), and the saponification value was (. - 0 mg/g KOH). The absorbance measurements at and 0 nm did not exceed the limit of.0 and 0.. The results of this study demonstrated that the studied Libyan olive International Journal of Chromatographic Science 0; (): - Sample site Alnowahi-- No. 0 cultivars shows the best fatty acid composition (lowest palmitic acid, which is the major saturated fat and they have high levels of mono- unsaturated oleic acid). All the samples were found to contain an oleic acid (C:) ranging from. % to. %.. References. A. K. Kiritsakisa, K. Kiritsakisc., Chemical Analysis, Quality Control and Packaging Issues of Olive Oil, Eur. J. Lipid Sci. Technol., 0 (00),. R. F. G. Abouzar Hashempour, D. Bakhshi, S. A. Sanam, Fatty Acids Composition and Pigments Changing of Virgin Olive Oil (Olea Europea L.) In Five Cultivars Grown in Iran, Aust. J. Crop Sci. (00), -. F. B. Samia Dabbou, S. Dabbou, M. Issaoui, S. Sifi, and M. Hammami, Antioxidant Capacity of Tunisian Virgin Olive Oils From Different Olive Cultivars African, J. Food Sci. Technol., (0), -. Kowalski, R., GC Analysis of Changes in The Fatty Acid Composition of Sunflower and Olive Oils Heated With Quercetin, Caffeic Acid, Protocatechuic Acid, and Butylated Hydroxyanisole, Acta Chromatogr., (00), -

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