Kirikaeshi (turning over the rice in koji making)

Kirikaeshi is an important step in koji making during sake production, and refers mainly to the work of mixing the piled-up steamed rice. It is carried out about 10 to 20 hours after tokomomi (the initial mixing of the rice after it has been inoculated with koji spores). At this stage the koji mold begins to grow actively, which makes the temperature and moisture inside the steamed rice uneven. Kirikaeshi loosens the steamed rice and brings it to a uniform condition, while also supplying it with oxygen. This keeps the koji mold active and promotes the production of high-quality koji. In recent years, koji-making methods that omit kirikaeshi have also been used, but in traditional methods this step is regarded as extremely important.