Optimization of Fermentation Process of Panax quinquefolius L. by Schizophyllum commune and Its Antioxidant Capacity in Vitro

In order to improve the economic value of Panax quinquefolius L., this study used Panax quinquefolius L. as raw material to solid state ferment Panax quinquefolius L. by Schizophyllum commune, increased the content of active components in Panax quinquefolius L., and optimized the fermentation technology. In this study, the total ginsenoside content of Panax quinquefolius L. was used as the indicator. First, strain 2 was selected from three strains of Streptomyces as the solid state fermentation strain for Panax quinquefolius L.. Then single factor experiment was conducted on four factors affecting total ginsenoside content. The four factors included: fermentation temperature, inoculation amount of Schizophyllum commune, pH value and fermentation time. On the basis of these results, the technology of solid state fermentation of Panax quinquefolius L. by Schizophyllum commune was further optimized by response surface Box Behnken experimental design. The optimized process conditions were determined as follows: inoculation amount of Schizophyllum commune 10.90%, fermentation temperature 31 ℃, fermentation time 10 d, pH value 5.9. Under the above conditions, the total ginsenoside content of Panax quinquefolius L. fermented by Schizophyllum commune was 10.28%, the content of crude polysaccharide was 12.85%, and the content of total flavonoids was 0.67%, which were higher than that of unfermented Panax quinquefolius L., and the contents of macromolecules ginsenoside Rb₁, Rg₂ and Re decreased, while the contents of micromolecules ginsenoside Rg₁, Rc, Rb₂, Rd, Rg₃, s-Rh₂, r-Rh₂ and pseudo-ginsenoside CK increased. Among them, rare ginsenoside Rg₃, s-Rh₂, r-Rh₂, and pseudo-ginsenoside CK were new saponins. In vitro antioxidant tests showed that the IC₅₀ values of DPPH and ABTS⁺ free radicals scavenging ability of the fermented products of Panax quinquefolius L. by Schizophyllum commune were 3165 and 10910 μg/mL, respectively, which were stronger than those of unfermented Panax quinquefolius L.. This study proved that the solid state fermentation of Panax quinquefolius L. by Schizophyllum commune increased the contents of total ginsenoside, crude polysaccharide, total flavone and rare ginsenoside, and enhanced the antioxidant capacity, which provided data support for the development and utilization of Panax quinquefolius L..