The Effects of Geographic Region, Cultivar and Harvest Year on Fatty Acid Composition of Olive
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Journal of Oleo Science Copyright ©2016 by Japan Oil Chemists’ Society doi : 10.5650/jos.ess15270 J. Oleo Sci. 65, (11) 889-895 (2016) The Effects of Geographic Region, Cultivar and Harvest Year on Fatty Acid Composition of Olive Oil Şeyma Şişik Oğraş* , Güzin Kaban and Mükerrem Kaya Atatürk University, Faculty of Agriculture, Department of Food Engineering, Erzurum, TURKEY 25240 Abstract: In this study, the effect of cultivar, harvest year (2010 and 2011) and the geographic regions (Mediterranean, Aegean, Southeastern Anatolia, Marmara and Black Sea) on fatty acid compositions of olive oil was investigated. The proportions of palmitic acid and linoleic acid, which comprised most of the amount of fatty acids after oleic acid, showed variations according to the region and cultivar. The amount of linoleic acid was found higher in some cultivars than that of palmitic acid. In the Aegean, Marmara and Mediterranean Regions, no significant difference was observed between olive cultivars for oleic and linoleic acids. The highest linoleic and lowest oleic acid content were determined in the Black Sea Region. One cultivar (Butko) showed an oleic acid proportion below 55% in this region. The effect of the harvest year on the fatty acid composition of the samples was also found significant. In oils harvested in the second year, a decrease in the amount of linoleic acid was observed, while the amount of oleic acid increased. The highest oleic acid proportion was found in olive oils produced from harvests in the Aegean and Mediterranean regions. Key words: cultivar, fatty acid composition, geographic region, harvest year, olive oil 1 INTRODUCTION the olive cultivar grows6, 7). The fatty acid composition of The chemical composition of olive oil is evaluated in two olive oil has a key role in olive characterizations. The domi- groups: major and minor components. Triacylglycerols, nant fatty acid is oleic acid which ranges from 55% to 83%8). which constitute more than 98% of the total fat weight, are Furthermore, the olive oil contains some saturated fatty the major components of olive oil. Existing at 0.5 - 1.5% in acids such as palmitic acid which range 7.5℃ - 20%, the olive oil, many chemical components such as aliphatic and myristic acid which range 0.05% or less in olive oil9, 10). triterpenic alcohols, sterols, tocopherols, hydrocarbons and Olive is grown in a large geographic area in Turkey, antioxidants are the minor components of olive oil1, 2). which is a significant olive producer, and olive oil is eventu- The highest amount of olive is produced in the Aegean ally produced. However, studies on the characterization of region in Turkey, followed by Marmara, Mediterranean, olive oil have only concentrated on specific regions and va- Southeastern Anatolia and Black Sea regions, respective- rieties11-19). Therefore, this study included exemplification ly3). More than 80 olive species are grown in Turkey. Al- that considers 5 different regions(Mediterranean, Aegean, though some species like Gemlik, Memecik and Ayvalık can Southeastern Anatolia, Marmara and Black Sea), exten- be grown in more than one region, species are often specif- sively produced cultivars per region and two harvest years, ic to the region. For example, Domat is a species which is and the olive cultivars were analyzed in terms of fatty acid endemic to the Aegean region, as Saurani to the Mediterra- composition after being processed to the olive oil in agri- nean region, Nizip Yağlık to the Southeastern Anatolia, cultural facilities. Butko to the Black Sea region and Çelebi to Marmara4). The quality of olive oil depends on a lot of factors such as olive cultivar, climatic and geographic regions where the olives grow, the maturity degree of the olive fruit which will 2 EXPERIMENTAL be processed to the oil, agricultural implementations and In this study, the fruits of five olive cultivars were har- olive oil production process5). The mostly, olive oil quality vested from five different geographic regions(Black Sea, is related to the olive cultivar and geographic region, where Southeastern Anatolia, Mediterranean, Aegean and *Correspondence to: Şeyma Şişik Oğraş, Atatürk University, Faculty of Agriculture, Department of Food Engineering, Erzurum, TURKEY 25240 E-mail: [email protected] or [email protected] Accepted June 13, 2016 (received for review November 23, 2015) Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 online http://www.jstage.jst.go.jp/browse/jos/ http://mc.manusriptcentral.com/jjocs 889 Ş. Ş. Oğraş, G. Kaban and M. Kaya Table 1 Olive cultivars from different geographic regions. Geographic region Southeastern Mediterranean Aegean Marmara Black sea Anatolia Gemlik Memecik Nizip Yağlık Gemlik Butko Ayvalık Domat Ayvalık Ayvalık Otur Cultivar Saurani Uslu Kilis Yağlık Çelebi Görvele Haşebi Gemlik Halhalı Domat Satı Sarı Ulak Erkence Karamani Memecik Kızıl Satı Marmara Regions)( Table 1). This experiment was repeat- chromatography(GC, Agilent Technologies 6890N)with ed during two years, 2010 and 2011 in November. The olive FID detector. GC system was equipped with a capillary fruits were processed to oil in agricultural facilities of the column(DB23, 60 m×250 µm×0.15 µm). The oven tem- regions, where the samples were taken. Five hundred mL perature was increased from 100 to 200℃ with rate of 5℃/ oil was taken from each sample, put into brown glass min and from 200 to 250℃ with a rate of 4℃/ min. The in- bottles and kept in dark until the analysis. jection block and detector temperatures were 250℃ and 280℃, respectively. Helium was used as a carrier gas with 2.1 Fatty acid compositions analysis a 1.2 mL/ min flow rate. A fatty acid methyl ester mix Fatty acid methyl esters were prepared from olive oil ac- (Supelco, FAME-mix, 4 - 7801, Bellefonte, PA, USA)was cording to the method described by Metcalfe and used as standard in the system Schmitz20). 0.05 g of sample was weighed and 1.5 mL of 2 M NaOH(methanolic)was added. The vials were capped 2.2 Statistical analysis under nitrogen gas, and a saponification reaction was The research was established and conducted on the carried out at 80℃ for 1 hour. Samples were cooled and 2 basis of the nested classification model considering 5 dif- ml BF3 - methanol was added. Subsequently, the tubes ferent regions, 5 varieties from each region and 2 harvest were again treated with nitrogen gas and allowed to stand seasons. The research data were subjected to variance for 30 min at 80℃. After cooling, 1 mL of hexane and 1 mL analysis through a packaged software(IBM SPSS Statistics of deionized water was added to the tubes and mixed well. 20)and the variation sources that were found important The tubes were centrifujed for 10 minutes at 6000 rpm. were compared with the Duncan’s multiple comparison Hexane layer was transferred to new tubes containing test. The relationship between harvest year and fatty acid sodium sulfate. After addition of 1 mL of hexane, 2 mL of composition as regions was also evaluated by principal the upper layer were transferred to vials. Vials were sealed component analysis(PCA)using Unscrambler v10. 01. under nitrogen and was maintained until analysis at - 18℃. (Como Process, A. S., Norway). Fatty acid composition of samples were determined by gas Table 2 The comparison of fatty acid compositions of olive oil which growing in different regions(mean±SD). Geographic region Fatty acid Southeastern Mediterranean Eagean Marmara Black sea Anatolia Palmitic acid (C16:0) 13.59±1.77b 11.20±1.72a 14.56±1.36b 10.74±1.99a 10.87±1.44a Palmitoleic acid (C16:1) 1.15±0.37bc 0.84±0.36a 1.33±0.22c 0.88±0.31a 1.10±0.20b Heptadecanoic acid (C17:0) 0.07±0.09a 0.05±0.07a 0.09±0.09a 0.17±0.10b 0.08±0.11a Heptadesenoic acid (C17:1) 0.22±0.08a 0.23±0.14a 0.29±0.09ab 0.31±0.10b 0.29±0.16ab Stearic acid (C18:0) 2.41±1.89b* 1.79±2.17ab 2.46±1.31b 0.98±0.89a 1.67±0.71ab Oleic acid (C18:1) 67.20±3.53a 70.68±4.55b 65.59±4.27a 73.31±4.23b 64.52±8.05a Linoleic acid (C18:2) 10.90±3.22ab 10.37±2.34ab 10.52±2.26ab 8.10±1.76a 11.99±2.47c Linolenic acid (C18:3) 0.72±0.15b 0.82±0.12c 0.85±0.11c 0.64±0.11a 0.59±0.12a Arachidic acid (C20:0) 0.29±0.11a 0.25±0.11bc 0.20±0.17b 0.29±0.08c 0.10±0.12a *a - c: Any means in the same column having the same letters are not significantly different (p>0.05), SD; standard devision. 890 J. Oleo Sci. 65, (11) 889-895 (2016) Fatty acid composition of olive oil Fig. 1 Principal component scores and factor loadings from PCA applied to the fatty acid composition. 891 J. Oleo Sci. 65, (11) 889-895 (2016) Ş. Ş. Oğraş, G. Kaban and M. Kaya Table 3 T he effect of the harvest year on the fatty acid composition of olive oil(mean±SD). Harvest year* Fatty Acid First Second Palmitic acid (C16:0) 12.04±2.25a 12.35±2.32a Palmitoleic acid (C16:1) 1.15±0.32b 0.97±0.35a Heptadecanoic acid (C17:0) 0.10±0.11a 0.08±0.09a Heptadecenoic acid (C17:1) 0.32±0.15b 0.22±0.06a Stearic acid (C18:0) 1.61±0.95a 2.12±1.99a Oleic acid (C18:1) 66.74±4.99a 69.78±6.65b Linoleic acid (C18:2) 11.84±2.67b 8.91±1.87a Linolenic acid (C18:3) 0.79±0.14b 0.66±0.14b Arachidic acid (C20:0) 0.19±0.16a 0.26±0.10b *1: 2010 harvest year, 2: 2011 harvest year.