Prolonging the oxidative stability of walnut oil by endogenous antioxidants: Phytosterol compounding for improved antioxidant capacity

Walnut oil, loaded with unsaturated fatty acids, offers significant health advantages yet is greatly vulnerable to oxidative spoilage.The investigation explored the impact of four oil extraction techniques on the inherent antioxidants, fatty acid profiles, antioxidant efficacy, and oxidation stability index (OSI) of walnut oil. The investigation utilized variance analysis coefficients and partial least squares regression analyses were conducted. It identified β-sitosterol and stigmasterol as crucial inherent antioxidant compounds. The maximal concentrations achieved through hot pressing were 943.16 mg/kg for β-sitosterol and 121.54 mg/kg for stigmasterol. Stigmasterol contribution to the DPPH radical scavenging activity was found to be 0.8224 in PLS1 (R²>0.95). Consequently, the combined effect of these antioxidants on the OSI was tested., revealing that a 2:1 ratio of these substances, under conditions of 45 ℃ ultrasound temperature and 27 minutes ultrasound duration(p<0.05), improved the OSI from 2 to 6.42.