Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

Browse

Filters

2014 - 20202

Settings

Author: search.filters.author.Özdemir, DurmuşSubject: search.filters.subject.Olive oil

Search Results

Now showing 1 - 2 of 2
  • Master Thesis
    Development of Molecular Fluorescence Spectroscopy Based Multivariate Calibration Models for Quantitative Determination of Fatty Acids and Triacylglycerol Compositions of Olive Oils
    (01. Izmir Institute of Technology, 2020) Hedef, Onur; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 01. Izmir Institute of Technology; 04. Faculty of Science
    This study illustrates the quantitative determination of fatty acid and triacylglycerol composition of olive oils by using multivariate calibration methods namely partial least squares (PLS) and genetic inverse least squares (GILS) coupled with molecular fluorescence spectroscopy. The reference analysis of the olive oils was carried out with gas chromatography (GC) and high-performance liquid chromatography (HPLC) for the compositions, respectively. A total of 125 olive oil samples were collected from Marmara and Aegean olive growing regions in western Turkey, right after the olives oils are produced in the 2010 -2011 season. Chromatographic and fluorescence analyses were performed simultaneously on the samples and then collected spectra were combined with reference analysis results for the multivariate calibration step. Among the several components analyzed by both GC and HPLC, 10 components from fatty acids and 10 components from triacylglycerols were chosen for modeling. Multivariate calibration models were constructed by randomly selecting 100 samples as calibration set and assigning the remaining 25 samples to the independent validation set using PLS and GILS with leave one out cross-validation based on the fluorescence spectra of the olive oils. The results have demonstrated that the compositions could be successfully determined by using molecular fluorescence spectroscopy. The standard error of cross-validation (SECV) and standard error of prediction (SEP) values were acceptable for most of the components. The regression coefficients (R2) of reference values vs. predicted values ranged from 0.70 to 0.98, indicating that molecular fluorescence spectroscopy combined with multivariate calibration could potentially be used for quantitative determination.
  • Master Thesis
    Development of Molecular Spectroscopic Multivariate Calibration Models for the Determination of Fatty Acid and Triachyl Glycerol Compositions of Olive Oils
    (Izmir Institute of Technology, 2014) Kuday, Esra; Özdemir, Durmuş; Özdemir, Durmuş; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    The determination of fatty acid methyl esters and triachyl glycerol compositions of olive oils by chromatographic methods require not only sample pre treatment carried out but also extend the time of the analysis. Also, chromatographic methods are expensive. Therefore, there is a need for an alternative method. In this study, it is aimed to develop molecular spectroscopic multivariate calibration models for the determination of some of the fatty acid methyl esters and triachyl glycerol compositions of olive oils. For this purpose, 79 olive oil samples from different regions of Turkey (Manisa and Bursa) were collected and scanned with Fourier Transform Infrared spectroscopy equipped with attenuated total reflectance (FTIR-ATR) accessory, Fourier Transform Near Infrared spectroscopy (FTNIR) and Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC). Chromatographic analyses of these samples were done by Olive Oil Research Institute and spectroscopic analyses were done by our group. The data obtained from High Performance Liquid Chromatography (HPLC) was chosen as a reference method for triachyl glycerol compositions and also the data obtained from Gas Chromatography (GC) was chosen as a reference method for fatty acid methyl esters. Also, Genetic inverse least squares (GILS) and Partial least square methods (PLS) were used for multivariate calibration. In conclusion, NIR and FTIR combined with multivariate calibration models can be more advantageous compare to chromatographic methods because of their simplicity and speed. When investigating the results, relatively successful calibration models were obtained from GILS method than PLS method.