Researches in the recent two decades, states that human nutrition plays a main role in development or prevention of chronic diseases such as cancer, heart-cardiovascular diseases, obesity and diabetes. Epidemiological studies indicate that consumption of fruits, vegetables, cereals, nuts and foods with low processing, provides the best protection against the spread of diseases. Pistachio is one of the most popular nuts all around the world which is known as green gold due to its high economic value. Since pistachio has some positive effects on human such as control of cholesterol levels, preventing heart-cardiovascular diseases and antioxidant properties, it is located in the consumer interest. Roasting process is a pretreatment for oilseeds before oil extraction. The purpose of roasting in food processing is improving the quality and safety of foods like soybean, hazelnut, coffee, pistachio, almonds, walnuts, wheat, coconut and sesame. One of the most favorable results of roasting process is increasing in antioxidant activity which is mainly due to the formation of mailard reaction products. Due to the efforts to prevent the oil oxidation and enhance its stability, roasting process can be a good way to increase oil stability in nuts. The aim of this study was to evaluate and compare the properties of the oil of both domestic and wild pistachio cultivars before and after the roasting. Roasting was performed by two methods of oven at 180°C for 15 minutes and microwave with 60 HZ -frequency for 5 min. After roasting, some chemical properties of pistachio nuts including moisture, protein and fat were measured. Oil extraction was performed for raw and roasted pistachios using soxhelet method and the oils properties were evaluated. Then, the extract residual meal was prepared its phenolic content and antioxidant activity were determined. The results showed that the domestic and wild pistachios contained a high percentage of oil (respectively 57 and 46%). Oil analysis indicated that the most parameters were influenced by microwave roasting probably because of its high tempreture. However, oven roasting only had more impact on the level of thiobarbituric acid (TBA) compared to microwave. Phenolic content of pistachio meal extract were in the range of 915-797 mg Gallic acid in kg oil and its antioxidant properties showed little difference with synthetic antioxidant. Results showed that the extract of pistachio meal can be used as a good source of natural antioxidant. Generally, roasting process not only is effective on the flavor of pistachio but also with increasing of phenolic compounds and antioxidant properties can be an appropriate and inexpensive method to increase the oil stability.
