Characterization of Ayvalik (Edremit yaglik) extra virgin olive oils volatile compounds with SPME-GC/MS and Raman spectroscopy

Olive oil, which has a great importance for Mediterranean diet, and its consumption is rising around the world. Moreover, the "geographic indications", which are considered as an assurance of quality and enhance the product value, are becoming increasingly widespread in olive oils. Thus, newly proved and practical analytical methods are needed that can be used to distinguish geographically labeled similar products from other regions. Virgin olive oils are produced from olive tree (Olea europaea L.) fruits using only physical processes and can be consumed without refining processes. Growing area of olives and its climatic and agronomic properties, genetic factors (cultivar), harvest time, harvesting method and technological processes such as extraction, packing and storage conditions have critical influence on the virgin olive oils chemical composition. In this project, particularly "growing area or geographic origin" effect was investigated on early harvest "Ayvalik" extra virgin olive oils some chemical features. "Ayvalik" is the prominent olive cultivar around North Aegean Region in Turkey. It cultivated such an extensive area in this region; however, it was observed that there were limited researches about geographical characterizations of "Ayvalik" olive oils. For this purpose, "Ayvalik" olives were harvested from different geographic locations of Balıkesir, Canakkale, İzmir and Manisa provinces in 2012, 2013 and 2014 crop seasons by hand-picking. The olives were carried to laboratory immediately for extracting virgin olive oils. After, low temperature (20oC) and short time (30 min) malaxing, oil samples separated by vertical decanter. Then, oils filtered through a cotton filter and volatile profile (SPME-GC-MS), fatty acid composition (GC-FID) and oxidative stability (Rancimat test) were determined. Other quality parameters such as, free fatty acidity, peroxide and UV absorption (K232 and K270), color values as L, a* and b* were also measured. The results demonstrated that olive oil samples were classified as extra virgin olive oil and virgin olive oil according to Turkish Food Codex in terms of free acidity, peroxide, UV absorption (K232 and K270) values and fatty acid composition. The samples were found very rich in terms of positive attributes (green, floral and fruity notes) which were generated by LOX pathway enzymatically. Over the last decade, Raman spectroscopy was used in foods in order to detection of geographic origin in particular. In this study, Raman spectroscopy and chemometric modeling (PCA) of its huge data set were used in order to classify the growing area of virgin olive oil samples. Effectively clustered origins of samples altered between harvest seasons. Over all data evaluation was showed that monocultivar virgin olive oils from North Aegean Region could be partially separated by both Raman spectroscopy which was rapid and practical analyze method with chemometry. Moreover, it was truly observed the virgin olive oils chemical compounds differed on the basis of geographic origins. It is considered that outcomes obtained within the scope of the thesis for Ayvalik cultivar will make a significant contribution to the dissemination and control of geographic indications in our country on the basis of objective criteria.