An important step performed several times during the sake brewing process is the preparation of the rice. We prepare rice for the moto, then again for each step of the san-dan-jikomi, the three step addition of rice, koji and water to build up to the moromi or the main fermentation. Another addition is sometimes done new the end of moromi called yodan. The preparation of the rice is the same for each of these additions.
Rice preparation consists of washing, rinsing, soaking, draining, packing, steaming, cooling and finally adding it to the brew. Rice for koji also goes through the same process except rather than adding it to the brew it is inoculated and then incubated. But this will be covered in another article. Let’s cover each of these steps separately.
White rice, whether milled as table rice or milled to a higher degree specifically for brewing sake, has unwanted material on it that we need to remove. This material can simply be the rice flour from the milling process. However, sometimes other material is added to assist with milling, e.g., talc, and others are added to enhance or enrich the final product. The later often include several of the following: Folic Acid, Niacin, Iron, Zinc, Selenium and Vitamins B-1, B-12 and E. Washing the rice in cold water removes these particulates. This can remove iron that contributes to bad taste development in sake and surface powders that can cause the steamed rice to be stickier than we would like.
Once thoroughly washed the rice should be rinsed in cold running water to rinse away the particulates that have been washed free. In some cases you may choose to do both the wash and rinse in a single step with cold running water. You know you are done when the water that starts with milky white run off turns clear.
Now that we have clean milled rice we want to raise its water content up to 25-35%. Commercial brewers are very specific about how much water they want the rice to absorb. In fact they have different amounts for their various styles and whether the rice will be used for making koji or not. In some cases brewers use a stop watch to make sure the rice does not soak for too long and take up too much water. Anyway, soaking the rice in cold water is the method used. The time needed to reach the desired water up-take level depends on the temperature of the water as well as the type and milling rate (seimai-buai) of the rice.
As home brewers we will not need to be as particular about the amount of up-take but rather shoot for the general ball park. To hit this ball park using rice with a 60% seimai-buai soak the rice in cold water for one hour. If you are using rice milled as table rice, seimai-buai 90 to 93%, soak for two hours. While these times are close to best, the additional water up-take from much longer soaking period has only a small impact on the sake. For this reason, some brewers soak their rice over night to get an early start on steaming in the morning.
As you get better at brewing sake you may want to be more exacting in the water up-take level. To do this you can add an experiment for the particular type of rice you use. Wash and rinse some rice and divide it into 5 equal portions. Weigh and record the results. Place all portions into cold water to soak. At 30 minute increments remove one portion, thoroughly drain and weigh. The percentage water up-take is the final weight divided by the starting weight minus 1 with the result multiplied by 100. Plotting these five points against their soak time will give you a curve you can used to determine how long you should soak your rice for the up-take you desire.
%water up-take = ( --------------------- - 1 ) * 100
Getting back to the topic at hand, once the rice has soaked for the period we want it is time to start draining the rice. Leaving the rice sit in a colander, strainer or sieve for about an hour will do the trick. Once nicely drained it is time to prepare for steaming the rice.
To steam the rice we want to ensure steam has to rise up through our rice to get out of the pot. We control this with the proper packing of our drained rice into our steamer. We want to have an even layer of rice that covers the entire steamer base (or each level of the steamer we will use). Ensure the rice evenly covers the base out all the way to the walls of the steamer so no steam can find a quick path to escape without going through the rice bed. Laying down a layer of cheese cloth or butter muslin before packing the rice will ease clean-up.
With the rice packed into the steamer we are ready to steam. Steam the rice for 45 minutes. Be sure to check the water level in your steamer about half way through to make sure you have enough water to make it. Running dry can destroy your steamer, smoke your rice or both.
With the rice steamed, lay it out on something like a cookie sheet where it can cool and dry. While it is cooling break all the clumps apart so that all the individual grains are as separate as possible. The washing and rinsing steps help here; by removing the outer starchy coating on the rice there is less sticky surface after steaming. By the time you have the rice clumps all broken apart, the rice should be mostly cool or at least cool enough to move to the final step before use. If the rice is to be added to the brew as steamed rice, it should be cooled further with a little cold water. On the other hand it the rice is to be used for making koji it can be inoculated with koji-kin.
So there you have it, rice preparation for sake brewing, hhhoo-yah!