The extraction of polyphenols from Magnolia grandiflora was conducted by ultrasonic extraction with ethanol as solvent.The ethanol concentration,solid-liquid ratio,ultrasonic temperature and ultrasonic time were se-lected as influencing factors.On the basis of single factor experiment,the extraction conditions of polyphenol were studied by orthogonal test.The antioxidant stability of polyphenols was studied by UV irradiation,additives,oxi-dants,reducing agents,metal ions and heat treatment.At the same time,the antioxidant properties of polyphenols from leaves of Magnolia on oil matrix were studied.The results indicated that the optimum extraction conditions were as follows:ethanol concentration of 80％,material ratio of 1:16,ultrasonic temperature of 80℃,ultrasonic time of 40 min.The results indicated that polyphenol had a scavenging effect on DPPH free radical and hydroxyl radical and had better scavenging ability on DPPH free radicals.The results indicated that the polyphenols from leaves of Magno-lia could effectively delay the oxidation of vegetable oil and animal oil,and the antioxidant capacity increased with the increase of polyphenols from leaves of Magnolia.
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