Evaluation of Physicochemical Properties and Oxidative Stability of Persian Hazelnut (Corylus avellana L.) Kernel Oil Under Different Microwave Roasting Conditions

The aim of this study was to evaluate the physicochemical characteristics (extraction yield, color development, fatty acid profile, iodine value, saponification value, phytosterol profile(, DPPH radical scavenging activity and oxidative stability of cold pressed hazelnut oil extracted from microwave pretreated kernels (0, 2.5, 5 and 7.5 min, 600 W). The results showed that microwave pretreatment of persian hazelnut kernel increased the oil extraction yield, color development and phytosterol contents of all oil samples. Also, no significant differences (p≥ 0.05) were observed during microwave pretreatment in saponification value (188-191 mg KOH/g oil) and fatty acids profile of hazelnut kernel oil samples. The predominant unsaturated fatty acids in oil samples in all treatments were determined as oleic acid C18:1c (77.43-78.32%) and linoleic acid C18:2c (9.85-10.18%), respectively. The predominant phytosterols in oil samples in all treatments were determined as β-sitosterol, Δ-5-Avenasterol, Campesterol, Δ-7-stigmastanol and sitostanol. The highest DPPH radical scavenging activity were observed in oil samples of MW-0 (90.62%) and MW-2.5 (89.94%), respectively. In addition, peroxide value, anisidine value and totox value of control hazelnut oil (MW-0) and pretreated hazelnut oil (MW-2.5) at an oven temperature of 160 ° C at 0, 3, 6 and 9 h intervals were determined. Also oxidative stability index (OSI) was determined by rancimat test at 120 ° C. The results indicated that microwave pretreatment is a promising strategy for amplification of oil extraction yield and phytosterol contents in obtained oil from persian hazelnut kernels.