"Basically, the preparation method of soy sauce koji involves washing and soaking the rice grains overnight, steaming the well-drained soaked rice for about 60 minutes, rapidly cooling and breaking the lumps of rice, mixing uniformly the ash and starter, distributing in trays and incubating in a special room for about 5 days with in-between stirring of the mixture on the second day and the third day. The molded rice is thoroughly dried, packaged, and stored in cold room with low humidity. Strict observation of aseptic conditions is required at every step of the preparation."