Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - Scopus: 2Fatty Acid Alkyl Ester and Wax Compositions of Olive Oils as Varietal Authentication Indicators(Springer, 2022) Uncu, O.; Ozen, B.Minor components of olive oils can be good markers for their authenticity, which is a significant quality issue for this product. It was aimed to determine individual and total fatty acid alkyl esters and waxes as minor constituents of olive oil and to investigate their novel varietal authentication capability separately and in combination for three main olive cultivars grown in three distinct locations of Aegean Region of Turkey. In addition, basic quality and purity parameters as free fatty acid, K values and fatty acid profiles were also determined for the characterization of the samples. Olive oil samples from different cultivars had different fatty acid profiles and two of these varieties had similar quality parameters. Statistical analyses were conducted with orthogonal partial least squares discriminant analysis (OPLS-DA) to differentiate varieties with respect to their individual and combined parameters of fatty acid alkyl esters and waxes. For calibration sets, use of individual fatty acid alkyl esters profile resulted in 80% correct classification rate while waxes alone was 67% successful in classifying the olive oils according to variety. It was found that alkyl esters in combination with waxes were more effective in discrimination of olive oils with respect to cultivar compared to their individual forms and the correct classification rate for the generated model is 92% for calibration set. Since fatty acid alkyl esters along with waxes have effect on cultivar differentiation, they could have a potential as authentication tools for olive oil besides their known quality characteristics. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Article Citation - WoS: 1Citation - Scopus: 2Fatty Acid Alkyl Ester and Wax Compositions of Olive Oils as Varietal Authentication Indicators(Springer, 2021) Uncu, Oğuz; Özen, BanuMinor components of olive oils can be good markers for their authenticity, which is a significant quality issue for this product. It was aimed to determine individual and total fatty acid alkyl esters and waxes as minor constituents of olive oil and to investigate their novel varietal authentication capability separately and in combination for three main olive cultivars grown in three distinct locations of Aegean Region of Turkey. In addition, basic quality and purity parameters as free fatty acid, K values and fatty acid profiles were also determined for the characterization of the samples. Olive oil samples from different cultivars had different fatty acid profiles and two of these varieties had similar quality parameters. Statistical analyses were conducted with orthogonal partial least squares discriminant analysis (OPLS-DA) to differentiate varieties with respect to their individual and combined parameters of fatty acid alkyl esters and waxes. For calibration sets, use of individual fatty acid alkyl esters profile resulted in 80% correct classification rate while waxes alone was 67% successful in classifying the olive oils according to variety. It was found that alkyl esters in combination with waxes were more effective in discrimination of olive oils with respect to cultivar compared to their individual forms and the correct classification rate for the generated model is 92% for calibration set. Since fatty acid alkyl esters along with waxes have effect on cultivar differentiation, they could have a potential as authentication tools for olive oil besides their known quality characteristics.Article Citation - WoS: 61Citation - Scopus: 70Use of Ftir and Uv-Visible Spectroscopy in Determination of Chemical Characteristics of Olive Oils(Elsevier, 2019) Uncu, Oğuz; Özen, Banu; Tokatlı, FigenIt was aimed to predict fatty acid ethyl ester (FAEE), wax, diacylglycerol (DAG) and color pigment contents of olive oils by using rapid and non-destructive spectroscopic techniques (FTIR and UV-vis) individually and in combination. Prediction models were constructed by using partial least squares (PLS) regression with cross and external validation. FAEEs were estimated best with FTIR + UV-Vis spectroscopy (R-cv.(2) = 0.84, R-pred(2) = 0.90, and RPD = 3.0). PLS model with R-cv.(2) = 0.79, R-pred(2) = 0.71, and RPD = 1.9 was obtained for the estimation of 1,2 DAG using FTIR spectral data. Major pigments, lutein, pheophytin a and their derivatives and total xanthophylls were quantified successfully by FTIR + UV-Vis with a range of R-cv.(2) of 0.71-0.85, R-pred(2) of 0.70-0.84, and RPD = 1.5-2.5 values but the prediction of the rest of the pigments were poor (R-cv(2) = 0.60-0.76, R-pred(2) = 0.42-0.62, and RPD = 1.2-1.5). Combination of two spectral data resulted in average prediction of wax content of oils (R-cal(2) = 0.95, R-pred(2) = 0.75, and RPD = 1.9). FTIR and UV-vis spectroscopic techniques in combination with PLS regression provided promising results for the prediction of several chemical parameters of olive oils; therefore, they could be alternatives to traditional analysis methods.Article Citation - WoS: 34Citation - Scopus: 42Importance of Some Minor Compounds in Olive Oil Authenticity and Quality(Elsevier Ltd., 2020) Uncu, Oğuz; Özen, BanuBackground: Consumption and production of olive oils have been increasing steadily worldwide mainly due to proven health benefits and sensorial characteristics of olive oil. M the same time, rising demand makes it harder to protect olive oil genuineness; therefore, inauthentic products have been always a serious problem in olive oil industry. Scope and approach: Some minor compounds such as pigments (chlorophylls and carotenoids) including their derivatives pyropheophytins (PPPs), diacylglycerols (DAGs) and fatty acid ethyl esters (FAEEs) are all prominent compounds with their discriminatory and descriptive properties. Among several different approaches, use of these components to differentiate genuine and adulterated olive oils could be a promising choice since it is harder to mimic these compounds in fake mixtures. Recent studies focus on these compounds as authentication and quality tools for olive oil and potential of these compounds are aimed to be reviewed. Key findings and conclusions: Results from literature indicated that these parameters could be used in both authenticity and quality determination of olive oils with some limitations. Pigments were found to be more promising in geographical and/or varietal classification. All of the discussed components have successful applications in determination of olive oil quality with respect to storage history and oil grades. However, in detection of certain types of adulteration techniques such as soft deodorization, reviewed parameters did not work effectively alone. Regulations could be updated with these findings and use of combined parameters including discussed compounds could be further investigated for unsolved authentication problems.Book Part Citation - WoS: 7Citation - Scopus: 14Olive Oil Adulteration With Sunflower and Corn Oil Using Molecular Fluorescence Spectroscopy(Elsevier Ltd., 2010) Öztürk, Betül; Arıkan, Aysun; Özdemir, DurmuşAdulteration of olive oil with cheaper substitutes such as sunflower and corn oil is a major concern for the public. Rapid analysis methods are required for a quick and easy screening of possible adulteration attempts. Fluorescence spectroscopy coupled with a genetic algorithm-based multivariate calibration method allows the determination of olive oil adulteration with sunflower and corn oil. Because the standard error of prediction values are all below 1.30% (w/w) for the ternary set, fluorescence spectroscopy can be used as a fast screening method for possible olive oil adulteration with cheaper vegetable oils. In addition, the genetic algorithm used in the genetic inverse least squares (GILS) method is able to select and extract the most relevant information to build successful calibration models that have high predictive ability for the independent test samples.Article Citation - WoS: 30Citation - Scopus: 30Discriminative Capacities of Infrared Spectroscopy and E-Nose on Turkish Olive Oils(Springer Verlag, 2017) Jolayemi, Olusola Samuel; Tokatlı, Figen; Buratti, Susanna; Alamprese, CristinaThe potentials of Fourier transform (FT) near- (NIR) and mid-infrared (IR) spectroscopy, and electronic nose (e-nose) on varietal classification of Turkish olive oils were demonstrated. A total of 63 samples were analyzed, comprising Ayvalik, Memecik, and Erkence oils. Spectra were pretreated with standard normal variate and second derivative. Classification models were built with orthogonal partial least square-discriminant analysis (OPLS-DA), considering the single data sets and also the combined FT-NIR-IR spectra. OPLS-DA models were validated both by cross validation and external prediction. All the models gave good results, being the average correct classification percentages in prediction higher than 90% for spectroscopic data and equal to 82% for e-nose data. The combined FT-NIR-IR data set gave the best results in terms of coefficients of determination (0.95 and 0.67). Different e-nose sensors discriminated Ayvalik, Memecik, and Erkence oils, explaining their distinct aromatic profiles.Conference Object Kırınım Yöntemi Kullanılarak Zeytinyağındaki Tağşişin Belirlenmesi(Institute of Electrical and Electronics Engineers Inc., 2017) Ekici, Çağın; Dinleyici, Mehmet SalihBu çalışmada, faz kırınım yöntemi kullanılarak gıda sanayisindeki büyük sorunlardan biri olan zeytinyağındaki tağşişin belirlenmesi amaçlanmıştır. Örnek sıvı içerisine ideal geometriye sahip fiber optik batırılarak lazer ışığının kırınımı incelenmiştir. Kırınım alanının matematiksel ifadesi Fresnel kırınım teorisine göre nümerik olarak hesaplanmıştır. Matematiksel modelleme, deneyler sonucunda elde edilen normalleştirilmiş kırınım deseniyle karşılaştırılıp, sıvının kırıcılık indisi tahmin edilmiştir. Kırınım yönteminin sıvının kırıcılık indisi tahminindeki yüksek hassasiyetli rolü (10−5 mertebesindeki) zeytinyağındaki tağşişin belirlenmesine imkan sağlamıştır.Article Citation - WoS: 46Citation - Scopus: 57Barcode Dna Length Polymorphisms Vs Fatty Acid Profiling for Adulteration Detection in Olive Oil(Elsevier Ltd., 2017) Uncu, Ali Tevfik; Uncu, Ayşe Özgür; Frary, Anne; Doğanlar, SamiThe aim of this study was to compare the performance of a DNA-barcode assay with fatty acid profile analysis to authenticate the botanical origin of olive oil. To achieve this aim, we performed a PCR-capillary electrophoresis (PCR-CE) approach on olive oil: seed oil blends using the plastid . trnL (UAA) intron barcode. In parallel to genomic analysis, we subjected the samples to gas chromatography analysis of fatty acid composition. While the PCR-CE assay proved equally efficient as gas chromatography analysis in detecting adulteration with soybean, palm, rapeseed, sunflower, sesame, cottonseed and peanut oils, it was superior to the widely utilized analytical chemistry approach in revealing the adulterant species and detecting small quantities of corn and safflower oils in olive oil. Moreover, the DNA-based test correctly identified all tested olive oil: hazelnut oil blends whereas it was not feasible to detect hazelnut oil adulteration through fatty acid profile analysis. Thus, the present research has shown the feasibility of a PCR-CE barcode assay to detect adulteration in olive oil.Article Citation - WoS: 20Citation - Scopus: 21Geographical Differentiation of a Monovarietal Olive Oil Using Various Chemical Parameters and Mid-Infrared Spectroscopy(Royal Society of Chemistry, 2016) Uncu, Oğuz; Özen, BanuIncreased demand for monovarietal olive oils from local olive varieties with unique characteristics as well as regulations such as 'Protected Designation of Origin' makes it necessary to identify methods for geographical classification of this product. Geographical differentiation of olive oils from a local olive variety from nine distinct locations of a peninsula in the west part of Turkey is investigated by using mid-infrared spectroscopic data and several chemical parameters (total phenol content, fatty acid and phenol profile, total carotene and chlorophyll content and oxidative stability). The best differentiation with respect to geographical origin was obtained with partial least square-discriminant analysis (PLS-DA) of a combination of various chemical parameters. The fatty acid profile also provided good separation of geographic locations and was slightly better than mid-infrared analysis. The best separation was achieved with respect to palmitic, oleic and linoleic acid contents of olive oils. However, mid-infrared spectroscopy with the advantages of being environmentally friendly, cost effective and a fast method could also be used to differentiate monovarietal olive oils with respect to their growing locations by factors such as micro-climates, proximity of regions and position to the sea.Article Citation - WoS: 55Citation - Scopus: 59Prediction of Various Chemical Parameters of Olive Oils With Fourier Transform Infrared Spectroscopy(Academic Press Inc., 2015) Uncu, Oğuz; Özen, BanuVibrational spectroscopic techniques offer advantages such as rapid and accurate measurements with minimum sample preparation and waste generation. In this study, it was aimed at determining some important quality parameters (oxidative stability, colour pigments, fatty acid profile and phenolic composition) of olive oils by Fourier transform infrared spectroscopy as one of the vibrational spectroscopic methods. Partial least square calibration models were constructed in order to reveal any correlation between quality parameters and spectral data. Regression coefficients for developed models showed that oxidative stability (0.99), chlorophyll content (0.98), some major fatty acids (palmitic (0.87), oleic (0.94), and linoleic acids (0.97), saturated (0.91), monounsaturated (0.94) and polyunsaturated fatty acids (0.97)), hydroxytyrosol as a phenolic compound (0.97) and total phenolic content (0.99) were predicted successfully. Variable influence on the projection values indicated that palmitic, vanillic and cinnamic acids and hydroxytyrosol are the most significant contributors to oxidative stability of olive oils. © 2015 Elsevier Ltd.