Abstract: Ginseng extract was fermented by the probiotic Lactobacillus plantarum to investigate the changes in its active ingredients and antioxidant activities before and after fermentation. The contents of total phenols, polysaccharides, total flavonoids and ginsenosides in raw and fermented ginseng extract were determined, and their antioxidant activities were evaluated by determining three free radical scavenging capacities, reducing power and lipid oxidation inhibitory activity. The results showed that the contents of total phenols, total flavonoids increased, while the contents of polysaccharides and total saponins decreased after fermentation. Ginsenosides Rg1, Re, Rb1 and Rc were hydrolyzed into rare ginsenosides such as Ck, Rk1, Rh4, and Rg5 during the fermentation process, and their contents increased by 0.770 6, 0.734 8, 3.392 4 and 1.364 8 mg/g, respectively. The antioxidant capacity of fermented ginseng extract at concentrations of 0.5–20 mg/mL increased compared with that before fermentation, which was inextricably related to the increase in the contents of total phenols and total flavonoids and the generation of rare ginsenosides. This shows that the fermentation process can produce a large amount of rare saponins and increase the contents of phenols and flavonoids, which makes fermented ginseng extract have stronger antioxidant ability.

Key words: ginseng extract; fermentation; Lactobacillus plantarum; antioxidant