Characterizing the Phenolic Compounds in Iron Walnut Oil (Juglans sigillata Dode) Across Chinese Regions

This study examines the chemical composition and antioxidant properties of iron walnut oil (IWO) from different Chinese regions, using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry for analysis of phenolic compounds. Regional variations were identified in fatty acid profiles, with elevated α-linolenic acid levels observed in cooler climates and higher oleic acid content in warmer regions. Antioxidant properties, quantified using DPPH, ABTS, and FRAP assays, corresponded to both oil polyphenol content (up to 62.91 mg/kg) and γ-tocopherol concentrations (268.68-525.05 mg/kg). Nineteen phenolic acids and flavonoids were identified, including ellagic acid, gallic, p-hydroxybenzoic, syringic, vanillic acids, quercetin, caffeic acid, ferulic acid, p-coumaric acid, coniferol, and pinoresinol. This comprehensive analysis underscores the nutritional and therapeutic potential of IWO, and delineates the impact of geographic and environmental factors on its quality, providing a scientific foundation for further research and development aimed at enhancing food industry standards and exploring natural product chemistry.