Evaluation of physicochemical properties of sesame oil from local extraction stores of Mazandaran province

Sesame oil samples from cities of Mazandaran province were collected and analyzed for fatty acids composition, iodine value, saponification value, unsaponifiable matter, moisture and sedimentation contents, metal content, free fatty acids, peroxide value, anisidine value, as well as oxidative stability using Rancimat and Schaal oven tests and compared with national standards and international codex standards. Results of the authenticity tests (fatty acids composition, iodine value, saponification value and unsaponifiable matter) and some quality determination tests (iron and copper contents, free fatty acids and peroxide value) were in the ranges of the Codex standard and Iranian national standards for sesame oil. However, 78% of the samples had higher moisture content, 33% of the samples had higher sedimentation content and 11% of the samples had higher lead content than the standards. The average induction period of oxidation at 110 °C was 8.3 hours. The induction period of oxidation in the Schaal oven test was in the range of 21.9-31.9 days. 78% of samples had higher moisture content, 100% had higher free fatty acids content, and 100% showed lower oxidative stability than the national standards of frying and cooking. 22% of the samples showed peroxide value higher than that in national frying oil standard. Though the authenticity of the sesame oil samples from oil extraction stores was verified but the quality parameters of oils did not match the standards, completely. Because of incompatibility of the samples with standards and their low oxidative stability, they were not suitable for frying or long-term storage.