- (Preliminary) mixing of kōji pile
Kiri-kaeshi is the breaking down and mixing of the pile of mushi-mai which has been inoculated with tane-koji. It is usually carried out some twelve to sixteen hours after toko-momi (the process of spreading the rice out on a toko table and kneading it to spread the spores evenly throughout the batch). The koji -kin gives off heat as it begins to grow, so kiri-kaeshi (literally “cutting and turning”) is carried out. The temperature and moisture content in the centre of the mass differs from that at the surface, and the mixing evens out that variation and assists oxygen supply to the koji.
The timing of each process and the temperature and humidity of the koji-muro are adjusted using the hardness (or softness) of the koji-mai, the progression of temperature, aroma and texture as guidelines.
If the timing of kiri-kaeshi is early, there is a tendency for the result to be tsuki-haze style koji; if it is delayed, the tendency is towards so-haze, so kiri-kaeshi is a key part of the sei-kiku process.