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, are 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 are analyzed. The lowest and highest fat content of six WOS varieties are obtained as 2.41 and 5.41%, respectively. The results from saponification value, iodine value, and unsaponifiable matter tests on different varieties of WOSO are 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 is 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%), are the predominant TAGs in the WOSO. Oleic acid and ferulic acid are 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 is observed.Practical Applications: The main outcome of this study shows 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 can be of importance for its further application in different industries, including the food industry, cosmetics, animal food, etc. Results show 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 problems.The whole olive stone (WOS) is known as an important byproduct generated in the olive oil extraction. Special physicochemical properties of whole olive stone oil (WOSO) are shown that this oil is a rich source of polar phenol and bioactive compounds. Results are shown that fatty acids, sterols, and triacylglycerols composition of WOSO depend on the olive cultivar. WOSO has similar the physicochemical properties and bioactive content as olive oil.