Chemical properties of the oil from Pistacia khinjuk fruits growing wild in Iran

Abstract

17.82, 17.44, 5.73, 2.31, and 1.5%, respectively 2. A study of the chemical properties of the oil from the P. khinjuk fruits has not been done previously. Therefore, this study was undertaken to investigate the chemical properties of the oil from P. khinjuk fruits (PKF) grown in Iran and to compare its properties with those of P. vera L. cv. Ohadi kernel (PVOK) oil (the most plentiful cultivar of P. vera in Iran) used as the control. The chemical composition and characteristics of the PKF and PVOK oils are shown in Table 1. The percentage of saturated fatty acids (SFA) of the PKF oil (20.76%) was significantly higher than that of the PVOK (9.81%) oil. Among the monounsaturated fatty acid (MUFA), the percentage of palmitoleic acid (C16:1) in the PKF oil (5.94%) was about 6.6 times higher than that of the PVOK (0.98%) oil. There was no statistically signicant difference between the percentages of oleic acid of the two oils studied (51.91–52.05). The polyunsaturated fatty acids (PUFA) content of the PVOK oil (37.06%) was significantly greater than that of the PKF oil (19.52%). From the information stated above, the PKF oil showed a ratio of unsaturated and saturated fatty acids (USFA/SFA) (3.81) and a Cox value (2.66) that were lower than those of PVOK (9.18 and 4.46, respectively) oil, which makes it particularly resistant to oxidation. The PV of the PKF oil (1.99 meq per kg oil) was significantly greater than that of the PVOK oil (0.25 meq per kg oil) (Table 1). This indicates that the PKF oils were oxidized more than the PVOK oil. This might be due to its improper storage and handling conditions as compared with the PVOK oil. The IV, which is considered as a measure of oil unsaturation for the PKF and PVOK oils, was 85.15 and 110.78, respectively. The difference in IVs among the PKF and PVOK oils was due to their different fatty acid composition. The PKF oil has a greater SFA content (C16:0 and C18:0) and a lower PUFA content (mainly, C18:2) than those of PVOK oil. As shown in Table 1, the SN of the PKF oil (79.46) was significantly lower than that of the PVOK oil (125.71) and also much lower than that of common vegetable oils with an average SN range of 175–250. Because there is an inverse relationship between SN and weight of fatty acids in the oil, it can be inferred that the PKF oil contains a great number of fatty acids of high molecular weight 3. However, as can be seen in Table 1, the fatty acid composition of the oils studied cannot be the only reason for the considerable differences in their average molecular weight. In fact, their different wax and USM contents constitute the main contribution of these differences 4.