Determination of changes in the quality properties of natural extra olive oil produced from some oil olive (Olea Europaea L.) varieties grown in Nizip and Mardin during storage

In this study, olive oils produced from Derik Halhali, Melkabazi and Nizip Yaglik olive varieties by cold pressed (20±2 °C) technique were packaged in 100 ml amber glass bottles and stored at room temperature without light for 6 months. In this context, pomological properties of olives and free fatty acidity (FFA), peroxide value (PD), specific absorption (PS), total chlorophyll-carotenoid, color, total phenolic content (TFM), total flavonoid amount (TFVM), total antioxidant capacity (TAC), phenolic compound, fatty acid composition and volatile compound levels of olive oils were investigated. It was determined that olive oils were in compliance with the legal limits determined for virgin olive oil in terms of FFA, PD and PS (270 nm) levels at the end of storage. It has been determined that Melkabazi oil is natural olive oil class in terms of PS (232 nm) values at the end of storage, and Derik Halhali and Nizip Yaglik samples as of the 4th month. Nizip Yağlık and Derik Halhali olive oils conformed to the limits in terms of fatty acid compositions. It was determined that oleic and linoleic acids content of Melkabazi oil did not comply with the limits during storage. It was determined that the amounts of TFM, TFVM, TAK and total chlorophyll in all samples decreased at the end of storage. At the end of 6 months, the total amount of carotenoids increased in Derik Halhali and Melkabazi oils, while it decreased in Nizip Yağlık varieties. L* (brightness) values were listed as Nizip Yağlık>Derik Halhali>Melkabazi at the end of storage. Nizip Yağlık and Derik Halhali oils were determined to be greener at the end of storage compared to Melkabazi oil. While Melkabazi olive oil had the highest b* (yellowness) value at the beginning of storage, the b* value of Melkabazi oil was found to be the lowest at the end of 6 months. Oleuropein, catechin, caffeic acid, vanillic acid, p-coumaric acid, ferulic acid, pinoresinol, luteolin and apigenin compounds decreased over a 6-month period, while tyrosol and hydroxytyrosol compounds increased. The volatile aroma components showed significant differences with storage time.