Characterization of aroma, aroma-active, C-isotope ratios and bioactive components of olive oils and the effects of different harvest years on these compounds

In this study, olive oil from ten different varieties, namely Ayvalık, Memecik, Tavşan yüreği, Beylik, Gemlik, Halhalı, Sarı ulak, Haşebi, Nizip yağlık, and Kilis yağlık, which are important olive oil types in our country, was utilized, and the effects of variety and harvest year differences on the quality parameters of olive oils were investigated. Olive oil samples were obtained from three different harvest years, 2016, 2017, and 2018, from the regions of Izmir, Hatay, and Gaziantep. In the study, the general analyses of olive oils, C-isotope ratios, characterization of bioactive components, and sensory characteristics were determined. Aroma compounds and aroma-active compounds characterizing these olive oils were identified. LC-MS-DAD-ESI was employed for phenolic compound analysis, while GC-MS-Olfactometry was used for aroma-active compounds. According to the results, the free acidity value in all olive oil samples was found below 0.8%. According to the findings, it was determined that the harvest year and variety have significant effects on the quality parameters of olive oil, such as aroma, aroma-active compounds, and phenolic compounds. Among phenolic compounds, tyrosol and hydroxytyrosol, and among aroma-active compounds, (Z)-3-hexenal and hexanal, and (E)-2-hexenal compounds were prominent. Olive oils were classified as genuine olive oil based on their carbon isotope analysis results. As a result of olfactometric analysis of the samples, it was determined that pleasant floral and fruity scents were prominent in the Halhalı variety, followed by Beylik and Ayvalık varieties.