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    Öğe
    Evaluation of Olive Preservation Methods on Bioactive Constituents and Antioxidant Properties of Olive Oils
    (Springer, 2017) Irmak, Sahnur; Kadiroglu, Pinar; Otles, Semih
    The purpose of this study was to determine the effects of preservation methods on less salty natural black table olives by evaluating the extracted olive oils. For this purpose, olives of the Gemlik variety obtained in two harvest years were brined and dry salted with 2 and 4% levels of salt and packaged with vacuum and modified atmosphere (60% N-2 and 40% CO2) and treated with gamma irradiation (0, 1, 3, 5 kGy). The olive oil extraction process was applied to raw olives, olives after fermentation and olives at 4th and 8th months of storage time. Bioactive component analyses including total carotenoid, total chlorophyll, alpha-tocopherol analyses and antioxidant properties were performed along with determination of free fatty acids content (FFA) and peroxide values (PV). FFA and PV increased while alpha-tocopherol (TO), total chlorophyll (TCH), total carotenoids (TC) and antioxidant activity (DPPH center dot radical scavenging assay) values decreased with storage and increment of irradiation dosage. Principal components analyses (PCA) showed that olive oils were discriminated clearly according to harvest year, salt content and processing type (dry-salting and brining). Overall, this study revealed that chemical parameters of olive oils as the main component of the olives were affected by the harvest year, processing and preservation conditions along with fermentation and storage period of olives.
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    Öğe
    Olive Treasures: Unveiling Fruit and Oil Characteristics of Aegean Region Varieties in Turkish Germplasm Bank
    (Wiley, 2026) Sevim, Didar; Kadiroglu, Pinar; Koseoglu, Oya; Uyanik, Elif B.; Telli Karaman, Hanife; Yaman, Senay; Irmak, Sahnur; Susamci, Erkan; Ozturk Gungor, Feriste; Yildirim, Aysen; Gurbuz Veral, Melek; Kaya, Hulya; Hakan, Mehmet; Asker, Ozlem; Altunoglu, Yesim
    This study comprehensively evaluated the fruit and oil characteristics of 26 olive genotypes from 2016/17-2019/20. The research focused on physicochemical quality parameters and purity criteria to classify the oils as extra virgin olive oil (EVOO) and explore their genetic and biochemical diversity. All analyzed oils met EVOO standards for free acidity (<= 0.8% oleic acid), peroxide value, and UV absorbance (K232, K270), except one sample (Ters Yaprak). Phenolic content ranged widely (160.40-738.94 mg CAE/kg oil), correlating with oxidative stability (6.00-20.80 h). Oleic acid (65.29%-76.88%) and linoleic acid (5.63%-15.10%) were the dominant fatty acids, with variations linked to cultivar and climate. Total beta-sitosterol (93.59%-96.55%) and Delta 7-stigmastenol (0.18%-0.72%) were key markers for authenticity, though two samples exceeded Delta 7-stigmastenol limits. alpha-Tocopherol (159.91-423.48 mg/kg) was the primary antioxidant, with Memecik, Ayval & imath;k cultivars showing high levels. Phenolic content strongly influenced these attributes. Principal Component Analysis (PCA) revealed that phenolic content, oxidative stability, and fatty acid composition were the primary discriminators among cultivars. PCA results showed that variation in fatty acid, TAG, sterol compositions across 26 olive genotypes from 2016/17-2019/20 was primarily driven by genotype and harvest year, with no strong geographical clustering but distinct profiles for certain varieties such as Domat, Uslu, and E & scedil;ek Zeytini. Olive Varieties of the Aegean Region demonstrated exceptional quality, meeting EVOO standards with high phenolic and tocopherol content. Notable varieties such as Memecik, Ayval & imath;k exhibited superior oxidative stability underscoring their commercial and nutritional value. This study provides critical data for conserving genetic resources and promoting regional olive oils in competitive markets.