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Rice Soak Test

That time of year again to start making Sake.

This year I plan to use terracotta 2lb loaf pans, which are unglazed for koji production. Somewhere on the internet I found a site showing someone’s success using these items. I will soak the pans under water 1 day before using, which should allow moisture to be released at a constant rate. As they dry out, the koji should be at the stage where the moisture should be dropping a bit.

I also wanted to check to see how long it actually took to soak my rice.

Taking 3 dixie cups, I placed 1oz of rice into each cup and then added water to all three, starting at the same temperature.

At intervals I dumped a cup into a metal strainer and wiped the water away from the bottom of the strainer as I shook the rice around. I did this for 2 minutes to ensure on average most of the surface water was removed. I then placed the rice into a new dry dixie cup (tared) and weighed.

T +30 minutes, cup 1 was 1.33 oz
T +45 minutes, cup 2 was 1.34 oz
T +60 minutes, cup 3 was 1.35 oz

So on average after 30 minutes or so the rice has gained about 30% in water weight.

Some observations:
Rice seams to be translucent white before soak. Dull, white and translucent.

At T+30 the rice was marbled. Opaque white with much more clear blister like zones. The rice was a little crunchy.

At T+45 the rice was opaque throughout. Rice was less crunchy, closer to al dente.
Cup T+30 was matching Cup T+45 in rice characteristics.

At T+60 the rice was opaque white, the rice was al dente and finely crumbly when chewed.
Cup T+30 and T+45 had the same look and characteristics as the cup at T+60.

Some conclusions:
The rice pulls water easier into different zones of the kernel and it took about 30 minutes to achieve. The water then migrates from these zones and balances out the rest of the kernel.

Little water is gained beyond the initial uptake. It takes about a total of 60 minutes for the water to profuse into the kernel evenly, but only 30 minutes to pull all the water it will use.

All of this will change to some degree based on the type of rice used and the condition of the rice before soaking.

Anyone making more sake this year?


I will be brewing a bit of sake this winter if and when my TTB license comes through…!

I kinda wish I was living near your place, would love to check it out!

Good luck on the TTB license! Like following your blog, are you going to put in fermentation cams? :slight_smile:

Yes, and temperature probes, etc… the brewery will be instrumented like crazy. Its my only hope for making a consistent product.

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