Impact of malaxation on quality and compositional characteristics of edremit yaglık olive oil

Abstract

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.

Zeytinyağı üretim aşamalarının zeytinyağının fizikokimyasal özellikleri ve fenolik bileşenleri üzerine etkisi

“…The extraction steps caused the increase in free acidity of oils and the maximum acidity was observed after malaxation process because of increasing lipase activity. This was in agreement with data reported from other studies (Yorulmaz et al, 2017;Jimenez et al, 1995;Kalua et al, 2006). The lowest peroxide value was determined after decanter, with the range of 1.5 meq O2 kg -1 .…”

“…It can be seen that the peroxide value reduced with extraction steps progressed because peroxides are not a stable product. In a study of Yorulmaz et al (2017), free fatty acid and peroxide values of olive oil were founds as 0.63% and 6.22 mg O2 kg -1 oil after 20 min of malaxation process, respectively. Polari et al (2018) informed that malaxation time affected both free fatty acid and peroxide values.…”

“…Contrary to present study, Kula et al (2018) reported that total phenolic contents of olive oils increased from 150.70 mg kg -1 to 250.60 mg kg -1 with malaxation process at 30°C. Total phenolic content of olive oil belonged to Ayvalık variety was 191.23 mg kg -1 when olive paste was malaxation for 20 min (Yorulmaz et al, 2017). Stefanoudaki et al (2011) observed that total phenolic contents of olive oils were determined as 187.85 ppm for Coratina variety and 153.57 ppm for Koroneiki variety when kneaded for 20 min and extracted by 2-phase decanter.…”

“…Kula et al (2018) observed an increase in the linoleic acid content (from 9.9% to 16.4%) and a decrease in the palmitic and oleic acid amounts (from 12.6% to 11.2% and from 72.7% to 67.9%, respectively) of olive oil when the malaxation process applied at 30°C. After malaxation process for 20 min, the oleic, linoleic and palmitic acid contents of olive oil were determined as 70.35%, 11.98% and 13.64%, respectively (Yorulmaz et al, 2017). In some studies, fatty acid composition did not show differences with malaxation (Inarejos-Garcia et al, 2009;Jimenez et al, 2014).…”

“…Firstly, the crushing enables to extraction of oil from the intracellular oil vacuoles using the several crushing techniques, such as the stone mill, blade crusher, or hammer mill (Polari et al, 2018). The malaxation is a significant process by mixing the olive paste which breaks of the emulsion, enlarges the diameter of oil droplets, makes the separation process easier (Yorulmaz et al, 2017). According to the previous studies, an important difference is not observed in the chemical properties of olive oils such as free fatty acid and peroxide values by using method of crushing.…”