The aim of the study was to investigate the changes in olive oils obtained from Edremit yaglık cultivar during malaxation. For this purpose, olives were processed to olive oil in industrial scale, and during processing olive paste obtained after crushing were malaxed for eight different malaxation times. The olive oil samples were evaluated for their quality parameters, volatile compounds, fatty acid, and sterol profiles. Results showed that free fatty acids increased; peroxide values, chlorophyll and carotenoid content, hexanal concentration decreased; K232 and K270 values, total phenol and tocopherol content fluctuated throughout malaxation. Fatty acid and sterol composition remained unchanged toward kneading process. Polyphenoloxidase activity decreased to a limit and remained almost constant till the end of malaxation period; whereas peroxidase activity tended to increase up to 40 min malaxation and afterward it began to lose its activity. PCA enabled the grouping of samples obtained from long and shorter malaxing periods. Practical applications Change in quality and some compositional parameters of virgin olive oil from Edremit yaglık variety during malaxation were investigated. Results have shown that some properties of virgin olive oil are affected by malaxation time. It is also possible to regulate the volatile composition by changing the kneading time. The current work examines the relation between the enzymatic activity and oil quality throughout the process, as well. The findings of the current study might be considered useful for olive oil producers to obtain optimum quality olive oil.

The objective of the current study was to assess the influence of a modified crushing process and kneading operation on the quality parameters, volatile compounds, and the fatty acid and sterol profiles of virgin olive oil from the Edremit yaglik variety. In the study, olive oil samples were produced in two different processes. The first one was produced without malaxation and the second one was produced with the malaxing process. During crushing, the effect of different temperatures was tested. The results demonstrate that different crushing temperatures generally did not affect the amount of free fatty acids, or peroxide value. Total phenol contents were positively affected by the additional malaxation process. Fatty acids and sterol composition were not significantly altered at different crushing temperatures or during the subsequent malaxation application. PCA enabled a clear classification of the oils obtained from different processing techniques.