Abstract: With the trash stem as raw material,which was remained in the production process of glycoside from Stevia rebaudiana transplanted in China from South America,three biological preparations,namely Sc1,Sc2 and Sc3 were obtained by different processes. Their antioxidant activities were assessed by the method of 2,2-diphenyl-1-picryl hydrazyl(DPPH) radical assay,oxygen radical absorbance capacity(ORAC) assay and POV value. The results indicated that they have some certain DPPH radical scavenging activities,and the activities rise with the increase of concentration. When the addition amount of the Sc3 is 0.015%,its scavenging activity to DPPH radical reaches 92.21%,as 1.1 times as that of synthetic antioxidant BHT and as 5.5 times as that of natural antioxidant vitamin E,and especially its stability of the DPPH radical scavenging activity is better than that of BHT,vitamin E or vitamin C. Furthermore,the antioxidant activities of the Sc3 and natural fish sauce were assessed by the ORAC assay. Its ORAC value is 326.28 trolox μmol/ml,as 6.7 times as that of the natural fish sauce. Besides,the storage results of Scomber japonicus floss indicated that the Sc3 has good antioxidant effect at 0.2% addition level. So it is a novel,natural,safe and highly effective antioxidant biological preparation with great development value.

Key words: Stevia rebaudiana, biological preparation, antioxidant capacity