Phd Degree / Doktora

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Application of Non-Targeted Analysis Methods in Adulteration Detection and Prediction of Process Parameters of Vinegars
(01. Izmir Institute of Technology, 2023) Çavdaroğlu, Çağrı; Özen, Fatma Banu
Vinegar plays a multifaceted role in human diet, encompassing nutritive, functional, and taste-enhancing aspects. Quality of vinegar is influenced by quality of raw materials and production methods employed. Spectroscopic techniques offer distinct advantages in terms of speed and environmental friendliness, making them valuable tools for monitoring and controlling food production processes. This study has two major parts. In the first part, traditional and commercial grape vinegar production were monitored using both chemical parameters (total acidity, pH, brix, ethanol etc.) and mid-infrared (mid-IR) and UV-visible (UV-vis) profiles. These measured chemical parameters were predicted from spectral profiles in combination with multivariate statistical analysis techniques. In the second part, mid-IR, UV-vis and fluorescence spectroscopic techniques were used in determination of adulteration of both grape and apple vinegar with acetic acid and spirit vinegar at various ratios. Capability of spectroscopic methods combined with chemometrics were tested for prediction of various chemical parameters of vinegar as well as detection of adulteration of vinegar with different adulterants. Those techniques have proven to be effective in estimating the overall quantities of sugars, phenolics, flavonoids, and organic acids. Utilizing chemometric models with UV–vis and mid-IR data yielded high rates of correct classification, sensitivity, and specificity, particularly for adulteration levels exceeding 5% in vinegar. The performance of mid-IR spectroscopy demonstrated success in detecting the presence of spirit vinegar and acetic acid in apple vinegar. Overall, with this thesis, the usefulness of spectroscopic methods was highlighted by emphasizing the importance of chemometric tools for the parameter prediction and detection of vinegar adulteration.
Minor Components of Olive Oils as Indicators for the Authenticity of Virgin Olive Oils
(Izmir Institute of Technology, 2021) Uncu, Oğuz; Özen, Fatma Banu
Adulteration of olive oil is a major problem of olive oil industry and may result in health problems as well as unfair earnings. Especially after the update in EU regulations about the labelling of olive oils, a need is arisen to detect the mixtures of old and fresh olive oils. Improvements in detection methods could fall behind of the inventiveness of the fraudsters. Detecting and preventing adulteration could be a challenging task; therefore, new methods and solutions are always in demand to solve this problem. First purpose of this theses is to characterize Aegean region olive oils with respect to their quality parameters such as fatty acid alkyl esters, diacylglycerols, and pigment compositions and to investigate differentiation power of these parameters on harvest year and geographical origin in comparison with spectroscopic methods. It is also aimed to predict these quality parameters by the fast and environmentally friendly ultraviolet-visible (UV-vis) and mid-infrared (mid-IR) spectroscopic techniques in combination with multivariate statistical methods. Finally, the applicability of spectroscopic methods (UV-vis, mid-IR, fluorescent) to detect adulteration of fresh olive oil with old olive oil is investigated. Olive oils were successfully differentiated with respect to geographical location by spectroscopic methods, fatty acid alkyl esters and pigments. In general, prediction of investigated chemical parameters was achieved robustly with mid-IR spectral data except pigments which were estimated better with UV-vis spectral data. Fluorescence and mid-IR + UV-vis spectroscopies were successful in detecting old olive oils in fresh olive oils.

Phd Degree / Doktora

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