Antioxidant Capacity, Phenolic Composition and Physicochemical Characteristics of Whole Olive Stone Oil Extracted from Different Olive Varieties grown in Iran

Abstract

In this study, the physicochemical properties and bioactive contents of whole olive stone oils (WOSOs) extracted from six olive varieties, including Zard, Roughani, Mari, Shengeh, Koroneiki, and Manzanilla, cultivated in the city of Fasa, Iran, were investigated. Therefore, fatty acids (FAs), sterols and triacylglycerols (TAGs) contents, equivalent carbon number (ECN), saponification, iodine and unsaponifiable matter values, and phenolic contents of each WOSO were analyzed. The lowest and highest fat content of six WOS varieties were obtained as 2.41 and 5.41%, respectively. The results from saponification value, iodine value and unsaponifiable matter tests on different varieties of WOSO were respectively ranged from 192.27 to 192.30 (mg KOH/g fat), from 82.80 to 93.35 (mg I₂/g fat) and from 0.03 to 0.32 (%). β‐sitosterol was found as the predominant sterol in the WOSO. TAGs with one FA, triolein (OOO, 19.29%–28.12%), followed by TAGs with two FAs, oleic‐oleic‐linoleic (OOL, 17.36%‐23.93%), and then those with three FAs, palmitic‐linoleic‐oleic (PLO, 8.36%‐11.73%), were the predominant TAGs in the WOSO. Oleic acid and ferulic acid were respectively found as the predominant FA and phenolic compounds in the WOSO. The influence of the olive variety on physicochemical properties and bioactive contents of the WOSO was observed.

Practical applications: The main outcome of this study showed that the determination of FA, sterol and TAG compositions of WOSO can be applied for the differentiation of olive variety. In addition, determination of the main parameters of chemical properties and bioactive contents of WOSO could be of importance for its further application in different industries, including the food industry, cosmetics, animal food, and etc. Results showed that this oil can be used as a natural source of polar phenol compounds for human consumption. Using WOSO for human consumption or the pharmaceutical industry can help to reduce waste disposal problem.

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