Oil quality of pistachios (Pistacia vera L.) grown in East Azarbaijan, Iran

Pistachio nut as a strategic product has a special place from nutritional and economical points of view. Its quality can be affected by variety, growing origin and climate. In the present study, the chemical composition of pistachio nuts harvested from different parts of East Azarbaijan province in Iran (Jolfa, Marand, Soufian, Azarshahr and Islamic Island) was investigated. The nuts had oil content of 49.9 to 58.5% and moisture content of 35.2 to 47.9. The acidity, peroxide values and the oil stability index (OSI) of the extracted oil were 0.03 to 0.3%, 0.19 to 1.0 meq O2/kg oil and 12.4 to 17 h, respectively. In addition, the chlorophyll content was found to be 15 to 72 mg pheophytin/kg oil and the carotenoid content was 5.4 to 11.5 mg/kg. In the fatty acid composition of the oil samples, oleic acid was the main fatty acid (52.5–63.9%), followed by linoleic acid (27.1–37.2%), palmitic acid (4.6–10.3%), palmitoleic acid (0.6–1.2%), stearic acid (0.1–1.3%) and linolenic acid (0.3–0.4%). Total tocopherol content of the pistachio oil samples was (125–258 mg/kg oil) which γ-tocopherol was the main tocol (112–232 mg/kg oil), followed by δ-tocopherol (5.3–19.3 mg/kg oil) and α- tocopherol (1.2–6.1 mg/kg oil). Total sterol content of the samples found to be (1125–2784 mg/kg oil). The most abundant sterol in the oils was β-sitosterol (966–2419 mg/kg oil) and other detected sterols were Δ5-avenasterol (72.6–170 mg/kg oil), campesterol (47.4–128 mg/kg oil), Stigmasterol (12.3–27.8 mg/kg oil) and cholesterol (8.3–39 mg/kg oil). The obtained results showed that origin had significant effects on oil composition. These data can be used to evaluate the nutritional value and authenticity of the oils and as useful information in establishing standards. Keywords: Fatty acids, Phytosterols, Pistachio oil, Bioactive compounds