Abstract: Ginseng extract was fermented by Lactobacillus plantarum to explore the changes of active components and their antioxidant activity before and after fermentation. The contents of total phenols, polysaccharides, total flavonoids and ginsenosides in ginseng extract before and after fermentation were determined. The antioxidant activity of ginseng extract before and after fermentation was compared by measuring the antioxidant activity of three kinds of free radical scavenging rate, reducing power and lipid antioxidant ability. The results showed that after fermentation, the contents of total phenols and total flavonoids increased, while the contents of polysaccharides and total saponins decreased. During fermentation, the sugar groups of natural ginsenosides Rg1, Re, Rb1 and Rc were hydrolyzed to form new rare ginsenosides Ck, Rk1, Rh4, Rg5, etc., and their contents increased by 0.7706, 0.7348, 3.3924 and 1.3648mg/g, respectively. The antioxidant capacity of ginseng extract after fermentation at 0.5~20mg/mL concentration was higher than that of ginseng extract before fermentation (GE), which was closely related to the increase of total phenols, total flavonoids and the formation of rare ginsenosides. This shows that fermentation can produce a large amount of rare saponins and increase the content of phenols and flavonoids, which makes the fermented ginseng extract have stronger antioxidant ability.

Key words: ginseng extract, fermentation, Lactobacillus plantarum, antioxidation