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    Comparative analysis of phytosterol components from rapeseed (Brassica napus L.) and olive (Olea europaea L.) varieties
    (Wiley, 2006) Gul, Muhammet K.; Seker, Murat
    Phytosterols occur in relatively high concentration in the seeds of rapeseed (Brassica napus L.) and in lower concentration in olive (Olea europaea L.) oil. The aim of this research was to investigate some new rapeseed varieties and olive genotypes that are grown in Northwest Turkey and to compare the phytosterol contents of both crops. For rapeseed, the data were collected in the growing seasons 2004-2005 from a field experiment with 19 new rapeseed varieties and three replications. For olives, 21 different varieties were used in the 2004-2005 and 2005-2006 growing seasons. The separation and identification of free phytosterols and the analysis of their contents were successfully achieved using the capillary column-gas chromatographic method. According to the obtained results, for rapeseed, sitosterol (1.54-2.36 g/kg) was the major component of total phytosterols, followed by campesterol (0.02-1.58 g/kg) and brassicasterol (0.26-0.58 g/kg). Regarding the olive varieties, the sitosterol content changed between 1.03 and 2.01 g/kg, followed by avenasterol ranging from 0.07 to 0.44 g/kg. The brassicasterol, campesterol and stigmasterol contents did not affect the total amount of sterols. The total phytosterol content ranged between 4.25 and 11.37 g/kg for rapeseed and 1.29 and 2.38 g/kg for olives.
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    Determination and Comparison of Chemical Characteristics of Arbutus unedo L. and Arbutus andrachnae L. (Family Ericaceae) Fruits
    (Mary Ann Liebert, Inc, 2010) Seker, Murat; Toplu, Celil
    The fruits and leaves of Arbutus species are well known in folk medicine as antiseptics, diuretics, and laxatives in many parts of Turkey. Some chemical properties including pH, soluble solid content, titratable acidity, protein, moisture, ash, ascorbic acid, fructose, glucose, sucrose, total phenols, total antioxidant activity, and minerals were determined in fully matured Arbutus unedo L. and Arbutus andrachnae L. fruits collected from different sites of Canakkale, Turkey in 2006 and 2007. Total soluble solids, titratable acidity, protein, moisture, and ash content of A. unedo and A. andrachnae berries were on average 16.0% and 14.0%, 0.4% and 0.6%, 2.38% and 3.77%, 47.21% and 38.21%, and 2.82% and 4.35%, respectively. The mean values of ascorbic acid were 270.50 mg/100 g for A. unedo and 140.30 mg/100 g for A. andrachnae, which suggested that Arbutus berries contain high amounts of vitamin C. In the strawberry tree fruits, fructose and glucose were determined to be the major sugars. The analysis showed that fructose and glucose occurred in concentrations of 24.09% and 19.09%, respectively. However, ripe A. andrachnae fruits contained small amounts of fructose (4.12%), glucose (2.73%), and sucrose (0.16%) detectable by high-performance liquid chromatography analysis. The general order of abundance of the minerals was K>Ca>P>Mg>Na in whole fruit of the strawberry tree. The chemical composition of Arbutus fruits indicates that the fruits are good sources of minerals and ascorbic acid and that they are high in phenolics and antioxidant capacity and low in soluble sugars, especially A. andrachnae. The data should be useful for research purposes and for compiling local food composition tables. In view of its chemical composition, the use of Arbutus fruits in some food products may be suggested.
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    Possible chemical mechanism and determination of inhibitory effects of 1-MCP on superficial scald of the Granny Smith apple variety
    (Tubitak Scientific & Technological Research Council Turkey, 2016) Ekinci, Neslihan; Seker, Murat; Aydin, Fatma; Gundogdu, Mehmet Ali
    The effects of postharvest 1-methylcyclopropene (1-MCP) treatments on alpha-farnesene content, incidence of scald, and ethylene content of the Granny Smith apple were evaluated in this study. Harvested apples were treated with 1-MCP at concentrations of 312.5, 625, and 1250 ppb. The 625 and 1250 ppb doses were found to be the most effective in terms of quality protection during storage. For untreated fruits, symptoms of scald development appeared after 8 weeks in cold storage, whereas 1-MCP doses of 625 and 1250 ppb were effective in decreasing superficial scald in fruit after 24 weeks of cold storage. 1-MCP can inhibit oxidation of alpha-farnesene, which synthesizes during storage. This induces reactive oxygen species metabolism. 1-MCP introduces competitive behavior by breaking the balance between a-farnesene production and the antioxidative defense system, due to the Schenck ene reaction.
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    Prediction of olive quality using FT-NIR spectroscopy in reflectance and transmittance modes
    (Academic Press Inc Elsevier Science, 2009) Kavdir, Ismail; Buyukcan, M. Burak; Lu, Renfu; Kocabiyik, Habib; Seker, Murat
    Quality features, including firmness, oil content and colour (chroma, hue), of two olive (Olea europaea L.) varieties ('Ayvalik' and 'Gemlik') were predicted using Fourier transform near infrared (FT-NIR) spectroscopy. Spectral measurements of the intact olives were performed for the wavelength range of 780-2500 nm in reflectance and for 800-1725 nm in transmittance. Measurements of olive firmness, oil content and colour were performed, following the spectral measurements, using standard methods. Calibration models for prediction of olive quality features were developed using the partial least squares method, and they were validated by leave-one-out cross validation. Better prediction results were obtained for Magness-Taylor (MT) maximum force (firmness) for both varieties in transmission mode, with the coefficient of determination (R(2)) of 0.77 and the root mean squared error of cross validation (RMSECV) of 1.36 for 'Ayvalik'. Reflectance mode, on the other hand, had a lower R(2) value of 0.65 (RMSCV=1.82) for 'Ayvalik'. Similar results were obtained for MT maximum force prediction for 'Gemlik' olives. Oil content prediction for each olive variety was poor, due to the relatively homogenous samples. However, better oil content prediction was achieved for the pooled data with the R(2) value of 0.64 (RMSECV=0.05) in reflectance and 0.61 (RMSECV=0.05) in transmittance. Both FT-NIR reflectance and transmittance measurements gave good prediction of olive colour, with the R(2) values for chroma ranging between 0.83 and 0.88 in reflectance and between 0.85 and 0.92 in transmittance. Similar results for hue prediction were also obtained. These results demonstrated that FT-NIR spectroscopy is potentially useful for assessing internal and external quality attributes of olives. (C) 2009 IAgrE. Published by Elsevier Ltd. All rights reserved.
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    Screening and comparing tocopherols in the rapeseed (Brassica napus L.) and olive (Olea europaea L.) varieties using high-performance liquid chromatography
    (Informa Healthcare, 2008) Seker, Murat; Gul, Muhammet Kemal; Ipek, Meryem; Toplu, Celil; Kaleci, Niluefer
    Rapeseed and virgin olive oils are a good source of tocopherols. Tocopherols are the most important compounds having antioxidant activity in both crops. Little is known about the tocopherol contents of rapeseed and olive oil grown in Turkey. The aims of this research were to investigate some new rapeseed varieties and olive genotypes grown in northwest Turkey and to compare the tocopherol fractions and contents of both crops. For rapeseed, the data were collected in two growing seasons (2004-2005, 2005-2006) from a field experiment with 19 new rapeseed varieties. For olives, virgin olive oils produced from 21 different varieties were examined in the 2004-2005 and 2005-2006 growing seasons. The separation and identification of tocopherols and the analysis of their contents were successfully achieved using the high-performance liquid chromatographic method. According to the obtained results, gamma-tocopherol (44.200-118.900 mg/kg) was the major fraction of total tocopherol, followed by alpha-tocopherol (19.300-68.500 mg/kg) and delta- tocopherol (0.00-2.600mg/kg(1)) for rapeseeds. Regarding olive varieties, the alpha-tocopherol content changed between 52.000 and 194.750 mg/kg, followed by gamma-tocopherol ranging from 0.00 to 39.750 mg/kg. The total tocopherol content ranged between 83.900 and 173.800 mg/kg for rapeseed and between 52.100 and 213.075 mg/kg for olives. This study revealed that an important variability exists for tocopherol content and composition in rapeseed and olive varieties.
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    Şeftali-Nektarinlerde Aroma Biyosentez Genlerinin Karakterizasyonu, Dönemsel Aroma Gelişiminin İzlenmesi ve Aroma Yapısını Kontrol Eden Genlerle İlişkili QTL lerin Saptanması
    (2019) Seker, Murat; Ekinci, Neslihan; Gür, Engin; İpek, Ahmet
    Aroma yapısı sert çekirdekli meyvelerin kalite özelliklerinin degerlendirilmesinde ve tüketici begenisinin kazanılmasında agırlıgını giderek arttıran önemli bir faktördür. Ülkemizin yerel genotiplerinden olan beyaz nektarinler, meyvelerde aroma olusumu ve gelisimi, biyokimyasal sentez süreci ve genetik mekanizmaları degerlendirmek açısından son derecede elverisli genotiplerdir. Aromaya iliskin özellikler meyvecilikte en karmasık karakterlerin basında gelmektedir. Genetiksel oldugu kadar çok sayıda çevre kosulundan da etkilenebilmektedir. Bu özelligin hem moleküler genetik hem de kromatografik yöntemlerle incelenmesi çok az sayıdaki arastırma çerçevesinde ele alınmıstır. Çok yıllık meyve türleri içinde model tür olan seftali ve nektarinlerinlerde aromanın detaylı bir sekilde incelenmesi önemli bir arastırma konusudur ve diger meyve türleri için de örnek olusturmaktadır. 2015-2019 yılları arasında yürütülen ve TÜBITAK tarafından desteklenen bu arastırma projesinde seftali ve nektarinlerde aroma biyosentezinde rol alan genlerin tam uzunluktaki transkiptleri RACE (Rapid Amplification of cDNA Ends) yöntemi ile elde edilmis, ilgili genlerin ifadeleri meyve gelisimi ve olgunlasma süresince qPCR ile belirlenmistir. PpLOX1, PpLOX2, PpLOX3 ve PpLOX4 genleri; PpHPL1 geni; PpADH1, PpADH2 ve PpADH3 genleri ve PpAAT1 genlerinde anlatım çalısmaları yapılmıstır. Aynı süreçlerde kromatografi teknikleri ile aromatik bilesik miktarları ayrıntılı bir sekilde ortaya çıkarılmıstır. Bu çalısmalar kapsamında aroma yogunlugu ile öne çıkan Beyaz Nektarinler dikkate alınmıstır. Aroma analizlerinin yapılmasında Gaz Kromatografisi / Kütle Spektrometresi kullanılmıstır. Meyvelerde aromatik yapıyı olusturan uçucu bilesikler hassas bir sekilde belirlenmistir. Ayrıca, yapraklarda uçucu bilesiklerin degisimi de yine kromatografi teknikleri ile incelenmistir. Yapılan kromatografi analizleri ile Beyaz Nektarin, Cardinal ve Armking meyvelerinde C6 Bilesikleri, Aldehitler, Esterler, Alkoller, Ketonlar, Laktonlar, Terpenler ve Diger Bilesikler gruplarına giren aromatik bilesiklerin meyve gelisimi ve olgunlasması süresince degisimi irdelenmistir. Bu süreçte linoleik asit ve linolenik asit yag asitlerinin degisimi de degerlendirilmis; hexane, hexanal, ethyl acetate, hexyl acetate, benzaldehyde, ?-octalactone, ?-decalactone, ??decalactone bilesiklerinin sentez reaksiyonlarının öncül yag asitleri oldukları kuvvetli korelasyon iliskileri ile ortaya çıkarılmıstır. Çalısmadan elde edilen bulguların basta Prunus genetigi ve ıslah çalısmaları olmak üzere, aroma biyokimyası için de önemli sonuçlar ortaya koyacagı düsünülmektedir.