Abstract: In this study,the effects of extraction solvents,ultrasonic power,treatment time and ratio of solid to liquid were investigated by an uniform design experiment.Meanwhile,the scavenging activities of Broussonetia papyrifer seed oil on hydroxyl free radical and superoxide anion radical were determined.The results indicated that the influencing factors on extraction yield of B.papyrifer seed oil were in this order (from strong to weak):ultrasonic power,ratio of solid to liquid,treatment time.The optimized processing parameters were determined to be:ultrasonic power was 65%,treatment time was 7 min,ratio of solid to liquid was 1:12.Under the optimized extraction conditions,the extraction yield of B.papyrifer oil was 30.2%.The antioxidant activities of the oil were determined by DPPH and pyrogallol autoxidation assays.The results indicated that B.papyrifer seed oil had strong hydroxyl free radical scavenging activity,reaching 93.56%,but no superoxide anion radical scavenging activity.

Key words: Broussonetia papyrifer seed oil, ultrasonic power, extraction yield, hydroxyl free radical, superoxide anion free radical, antioxidant activity