Hatcho Miso

Yes — Hatcho Miso is registered under Japan's Geographical Indication protection system administered by the Ministry of Agriculture, Forestry and Fisheries (MAFF) as Registration No. 49. The registered protection restricts the protected name 八丁味噌 (Hatcho Miso) to producers operating in the designated Hatchō-chō district of Okazaki City, Aichi Prefecture, who follow the registered traditional production method (mame koji + kioke barrel + stone weights + multi-year aging). Soybean-only miso made elsewhere may be sold as 豆味噌 (mame miso) but cannot use the protected GI name.

Hatcho Miso is a mame miso (made from soybean koji only, with no rice or barley koji), produced from steamed soybeans inoculated with Aspergillus oryzae plus salt and a small amount of water. The mash is loaded into large cedar barrels (kioke) and pressed under a stacked pyramid of river-stone weights, then aged for a minimum of two years (traditionally up to three). The result is a very dark, low-sweetness paste with deep, slightly astringent umami, distinct from sweeter rice-koji-based varieties such as Shinshū or Saikyō miso.

Aspergillus oryzae (kōjikin) is the koji mold that secretes the enzymes converting soybean starches and proteins during fermentation. In Hatcho Miso, A. oryzae is grown directly on steamed soybeans to make mame koji (soybean koji), unlike rice or barley miso which use grain koji. A. oryzae was designated the national fungus of Japan (kokkin) by the Brewing Society of Japan in 2006 in recognition of its central role in sake, miso, soy sauce, and shōchū production.