Evaluation of physicochemical properties and antioxidant activities of Persian walnut oil obtained by several extraction methods

An analytical study on the fatty acids, physicochemical characteristics, phenolic compounds, tocopherol content and antioxidant activities of walnut oils extracted by different extraction methods (maceration, Mac; modified Bligh–Dyer, MBD; and cold-press, CP) was conducted. Antioxidant activity of oil was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzthiazoline sulfonate) (ABTS) radical scavenging capacity and β-carotene bleaching assays. Results showed that fatty acid content was not influenced by extraction method. MBD method was found to be the best process for extracting oil with a favorable quality characteristics when compared to Mac and CP. Higher total phenolics content (TPC), ortho-diphenol content (ODC) and total tocopherol content (TTC) and DPPH and ABTS scavenging capacities were also obtained with MBD. According to both principal component and correlation analyses, TPC and ODC were correlated with the β-carotene bleaching activity and TTC was correlated with the ABTS of the oils extracted by the different methods in the current study.

► Persian walnut oil indicated high functional compounds and antioxidant activity.
► Extraction method may change the properties of extracted oil.
► Modified Bligh–Dyer method provides extracted oil with better quality parameters.
► Principle component analysis was efficient to classify the oil minor compounds.
► Data of principal component analysis and correlation test were noticeably consistent.