Preparation of Chaga medicinal mushroom, Inonotus obliquus-fermented rice using solid-state fermentation and its taste quality and antioxidant property.

Chaga medicinal mushroom, Inonotus obliquus (Pers.:Fr.) Pilat, was inoculated into cooked embryo rice and the mycelial growth in I. obliquus-fermented embryo rice (IER) was monitored. Besides, nonvolatile taste components and antioxidant properties of fruiting bodies, mycelia, IER, and embryo rice were studied. The optimal conditions for mycelial growth were determined to be: 30°C, an inoculation rate of 1 mL/15 g, water supplementation of 60%, and no extra nitrogen source added. IER showed similar proximate composition to embryo rice but contained a substantial amount of ergothioneine (101 mg/kg dry weight). IER contained higher amounts of soluble sugars and polyols, and umami taste components, including monosodium glutamate (MSG)-like components and flavor 5'-nucleotides, than embryo rice. Besides, IER showed a second level of equivalent umami concentrations (223.73 g MSG/100 g). Fruiting bodies did not contain umami components but showed the most effective antioxidant properties. Although some of EC50 values of IER were less than those of mycelia and embryo rice, IER still showed effective antioxidant properties. Based on the results obtained, IER will be a novel functional food.