Determination of physicochemical properties of irradiated sumac(Rhus coriaria L.) fruit oils

In this study, it has been aimed to determine some changes on quality parameters and oxidative stability of oil obtained from sumac fruit irradiated with gamma rays at different doses. Sumac plants grown naturally in Sazlıdere village of Keşan district of Edirne were chosen as research material. Sumac fruits were divided into five equal pieces of 400 g and brought to GAMMA-PAK Sterilization Ind. & Trd. Inc. in Çerkezköy, Tekirdağ. Irradiation was applied to the four groups except the control group at 2.5, 5.0, 7.5 and 10 kGy doses respectively. After the irradiation process, the extraction of crude oil of sumac fruit samples was performed by soxhlet method and then free fatty acid content, peroxide number, fatty acid composition and tocol and sterol compositions of these oils were determined. Moreover, total phenolic content by using Folin-Ciocalteu reagent method and DPPH (2,2-diphenyl-1- picrilhydrazil) free radical reduction activity were determined. In parallel with the increase in irradiation dose, free fatty acidity and peroxide values of sumac fruit oil increased. When the fatty acid compositions were examined, the main fatty acid of sumac fruits was determined as oleic acid. In addition, as the irradiation dose increased; palmitic (C16:0) and stearic (C18:0) acid rates of saturated fatty acids and oleic (C18:1) monounsaturated fatty acids increased,while linoleic (C18:2) and linolenic (C18:3) acid as polyunsaturated fatty acids rates were determined. When the sterol and tocopherol composition of the sumac fruit oil was examined, it was seen that the most common sterol was β-sitosterol and irradiation did not cause a statistically significant change in the sterol composition, but the tocopherol composition decreased with increasing irradiation dose. Total phenolic content and antioxidant capacity value of Sumac fruit samples, were stated to decrease as the irradiation dose increased.