After polishing the rice, the next step in the sake making is process is washing and soaking. Washing is simple enough (if you have a nice little washer like they have here); the rice is washed in 10 kg portions for 1 min, dropped into a bag, rinsed gently for 30 sec, and is then placed into a container full of water to soak.
But how long should the rice be soaked for?
For rice to be used in making koji, the target amount of water to absorb is approximately 33% of the dry weight. For rice to be added into the fermentation directly(after steaming- called “kake mai”), the rice should absorb a little less water, around 29%. In the photo, Uei-san is writing down the times that rice should be placed in, and taken out of, the soaking containers. For the first bag, there is a little trial and error, with the rice being soaked, then weighed (after removing excess external water), then placed back in the water, then weighed again. For this batch of rice, which was called “Hinohikari” and was milled to 60%, it took 11 min 15 sec to soak up 29% the initial weight of water. Hope that helps answer the question!
Uei-san calculating the soaking time
Greg,
I had never heard of having a different water uptake target for rice to be used for koji vs. just added straight to the mash. What is the thinking behind this?
Thanks
Will,
I think it is related to the fact that koji rice is exposed to a warm and fairly dry environment for about 48 hours after steaming, so it desirable to have a higher content of initial water to avoid it from drying out too much.
But, I have not been told that from a toji or other reputable source, that is just my best guess.
regards,
Greg