The season’s first sake has been pressed and it is now time to start another batch (this will be batch #5). The first step is to make a yeast starter culture, which requires koji, steamed rice, water, and yeast. So the first step in making sake is to make koji (after growing the rice, of course) as it takes about 2 days. Although mentioned before, koji is a mold (Aspergillus oryzae) that when cultivated on rice at high temp (over 30C), secretes enzymes that turn the rice starch in sugar.
To make koji, the milled rice (we are using Hitogokochi milled to 60%) is washed for 1 min in a pressure washer in 10kg units, and then soaked for about 10-12 min. Once the rice has absorbed the right amount of water (around 30%), it then allowed to sit overnight. Tomorrow, this rice will put in the koshiki (large steamer) and steamed for about 1 hour. Until tomorrow then.