Cultivation process of koji mold

  • After polishing the rice, it is washed to remove any dirt, allowed to absorb enough water, then steamed. The steamed rice is cooled to approximately 35°C , and koji mold spores are sprinkled over the rice, and the mixture is stirred until uniform. The surface condition of the steamed rice is highly suitable for growing koji mold. After 8 hours, hyphae start to extend, although this is not visible by the naked eye. It will take 18 hours or more after the spores have been sprinkled to see the growth of the koji mold. After 18 hours, koji mold spreads hyphae over the surface of the rice, causing the surface to become white. As the surface of rice becomes covered with hyphae, the hyphae then start to turn upwards into the air. These hyphae produce spores, like branches that bear fruit. Hyphae first grow on the surface of the rice and perform the role of nutrient absorption, similar to plant roots, and are called as “substrate mycelia.” Upward hyphae which produce spores are called “aerial mycelia.” The number of aerial mycelium increases, and at the same time, spores formed on the top of the hyphae. At this time, fluffy hairs on the surface of koji mold appear and can be seen with the naked eye, and change to a yellow-green color. This increase in aerial mycelium and spore adhesion at the top continues until Day 5 of culturing, when the surface becomes covered with spores. Cultivation under the same conditions continues for two days until the spores mature and Tane-koji(seed koji) cultivation is complete. While this varies by type of koji mold, when cultivation of the Tane-koji(seed koji) is complete, more than 500 million spores per 1g are produced.

    Ingredient riceIngredient rice

    Condition after steaming Condition after steaming

    After mixed with ashAfter mixed with ash

    Day 1 of cultureDay 1 of culture

    Day 2 of cultureDay 2 of culture

    Day 3 of cultureDay 3 of culture

    Day 5 of cultureDay 5 of culture