Utilization of soybean curd residue for polysaccharides by Wolfiporia extensa (Peck) Ginns and the antioxidant activities in vitro

To reduce nutrient cost and improve the production of polysaccharides by Wolfiporia extensa (Peck) Ginns (F.A. Wolf), soybean curd residue (SCR), a food waste, was chosen as the nutrient source in this study. The objective of this research is to determine optimum culture conditions for solid state fermentative production of polysaccharides and evaluate the antioxidant activities. Response surface methodology (RSM) was employed to optimize the fermentation conditions of F.A. Wolf for the enhancement of polysaccharides. The optimal conditions were obtained by response surface methodology as follows: fermentation temperature 23.7 °C, fermentation time 7.5 days, and inoculum size 15.5 mL. Under optimized conditions, the polysaccharides yield reached 88.93 ± 1.87 mg/g, which was in close agreement with values predicted by the mathematical models. Furthermore, the polysaccharides exhibited positive antioxidant activities. This research provides references for the large-scale production of polysaccharides by F.A. Wolf and points to a new direction for SCR utilization.