Abstract:Taking oil-bearing peony seeds as raw material and oil yield as the evaluation index，this study optimized the ultrasonic-assisted aqueous enzymatic extraction（UAAEE）process of peony seed oil through singlefactor experiments and orthogonal experiments.It also systematically investigated the physicochemical quality and in vitro antioxidant activity of the extracted oil.The optimal extraction conditions were determined as follows：solid-liquid ratio of 1∶6（g/mL），papain dosage of 5 000 U/g，enzymatic hydrolysis pH of 5.0，enzymatic hydrolysis temperature of 50.0 ℃ and enzymatic hydrolysis time of 4 h.Under these optimized parameters，the peony seed oil yield reached 21.04%.Physicochemical analysis results indicated that the peony seed oil prepared by UAAEE exhibited sensory characteristics of being clear and transparent，free of visible impurities，and abnormal odors.Its key physicochemical indices were determined as follows：refractive index（n20）of 1.42±0.11，relative density（d20）of 0.92±0.02，acid value of（1.43±0.35）mg/g，iodine value of（17.63±1.12）g/kg，saponification value of（193.22±1.43）mg/g，and peroxide value of（0.87±0.16）g/kg.All the aforementioned indices fully complied with the requirements of relevant national standards，including GB/T 5492—2008 Inspection of grain and oils-Identification of colour，odour and taste of grain and oilseeds，demonstrating the excellent quality of the oil.In vitro antioxidant activity assays showed that the peony seed oil achieved maximum scavenging rates of 65.29%，55.47%，and 96.71% against 1，1-diphenyl-2-picrylhydrazyl（DPPH）radicals，hydroxyl radicals，and 2，2'-azinobis-（3-ethylbenzothiazoline-6-sulfonic acid）cation（ABTS）cation radicals，respectively.These results confirm that the peony seed oil extracted by UAAEE possesses favorable in vitro antioxidant activity.