Japan is the leading producer and consumer of maitake mushroom. The largest maitake producing company I have visited is in Gunnma Prefecture in North Central Japan and the white and dark brown Mori strains are most produced in that region today.
Commercial production of most G. frondosa is on sawdust substrate supplemented with rice bran in micropore fitted polypropylene bags. The substrate is filled into the polypropylene bags, sterilized and after cooling (14-20 hours), inoculated with spawn under sterile conditions. Spawn run lasts about 30 to 60 days depending on strain and substrate formulation. Temperatures then are lowered from about 22C to 14C to induce fruit body formation and maturation.
Although most maitake mushroom is sold as food, it has found its way into the preparation of nutraceuticals and dietary supplements like tea, fruit body powder, granules, drinks, and capsules. This is because this mushroom has been shown to have medicinal properties. Maitake glucans have been shown to have both anti-tumor and anti-viral properties. T cells and macrophages supposedly mediate the antitumor effects of G. frondosa glucans. Glucans are believed to exhibit various cellular responses, among which is cytokine expression and production.
The cultivation of maitake is on the rise in the United States today. It is possible to find them in the grocery stores here in North Carolina, although we do not know anyone growing this mushroom in North Carolina right now. A recent survey of mushroom buyers and marketers indicated that there is a market for maitake in North Carolina.