Mori (dividing the koji rice into boxes)

Mori is an important step in sake production and forms part of koji-making (seikiku). It is carried out about 12 hours after white mycelium begins to appear on the steamed rice. At this point, the steamed rice must be loosened and placed into boxes in fixed amounts. The purpose of mori is to encourage the activity of the koji mold and to make temperature control easier during the fermentation process. About 20 hours after the tokomomi step, the koji mold begins to multiply vigorously and the temperature rises naturally. If the rice were simply left as it is, a suitable environment could no longer be maintained. For this reason, the steamed rice is divided up using koji lids (koji-buta) or koji boxes (koji-bako) and kept at a steady temperature, which is required to produce good koji.