Closeup of Sake Production: Rice Washing

Greetings Sake Lovers, welcome to another KURAND Magazine article that introduces you to the world of sake.

Continuing on from the last article about rice polishing. This article will look in more detail at the next stage of the production process, rice washing. The rather menial sounding task of rice washing might not sounds like it would be worthy to dedicate an entire article, but nothing but could be further from the truth. What sounds like a very menial task is in fact another very important, essential part of the process that can heavily influence the final quality and style.

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Sake Making Process in a Nutshell


A very basic diagram of the sake brewing flow can be found in the chart above. This is just a very basic outline. The process varies depending on the variety of rice and the target style of sake. Seimai-buai plays a pivotal role in determining the end style and flavor, so it is definitely worthy of a more detailed explanation.

Washing the Rice

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Rice will have a lower water content after polishing than before due to the heat and friction of the polishing process, so the rice is put in a cool place to rest to reabsorb some of this lost moisture from the air. This is called karashi in Japanese.
Even after polishing, the rice is covered in tiny particles of rice bran that are simply too fine to completely polish away. To brew with rice in this state would completely defeat the object of polishing it in the first place. The solution of course is to wash. There is nothing special about washing rice before using it. We do the same for table rice before we cook with it. In brewing, the primary objective is to remove excess yeast nutrients such as potassium and protein, but it is about more than just washing. During the washing process, inevitably, water is absorbed by the rice. This moisture absorption must be controlled, which for the higher grades of sake like ginjo and daiginjo, etc, involves the use of a stopwatch. That’s right, someone actually stands there and times the washing — down to the millisecond in fact. Just an error of 0.5 could have a huge effect on the rest of the process. Furthermore, in the hours immediately following karashi, rice is very delicate and brittle. To avoid damaging the rice, the rice is washed very carefully. The traditional way is by hand, but there are now machines that do the job just as well, if not better. In fact, some brewers argue that machines handle the rice more consistently and reliably than people.

How Does Polishing Affect Sake?

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During the polishing process, the rice can absorb anywhere between 10-20% of its weight in water. The actual absorption rate greatly affects all the parts of the process that follow such as mushi-mai (steamed rice) and even more importantly, the koji making. The temperature of the water and length of washing is very important and varies depending on the type / quality of the rice, polishing ratio; and ultimately the target style, flavor and aroma. All of these factors vary with every variety of rice. And every year, as with wine grapes, the climate and condition of the soil can alter them quite dramatically. Thus, the length of polishing, temperature of water and target water absorption rate has to be adjusted every year. In most breweries, the final judgment falls to the toji and is where their skills really start to shine. Breweries that do not employ toji keep a yearly record of their washing.

How Difficult is Washing? The Brewers Explain

I only help out sometimes but doing senmai by hand is very cold. Senmai is done by putting water and rice into an oke (bucket) and washing it continuously for a few seconds. It is not a long time but it is so cold that it feels very long. (colder water slows the rate of absoprtion down and is necessary for making daiginjo)

Ms.Hasegawa, Hasegawa Shuzo

Basically everything is difficult haha. Compared to koji, shubo, and moromi, it looks easy so it is often overlooked. However, personally speaking, this is a complex stage that relies less on experience and more on raw skill. (I feel that no amount of experience or data will ever be enough to perfect this task).

Rice very much depends on the weather of that year and even the location where it is grown can make a difference. Thus, it is hard to predict what the rice is going to be like before we actually start washing. Currently, when washing the first batch of the year, we start out with 10kg to create a standard with which to calibrate the rate of absorption for the entire batch. We then basically use the those standards throughout adjusting where necessary.

Most people are able to imagine washing the rice but very few imagine letting the rice absorb water. This is a very different feeling from when we wash rice at home before we cook it. Deciding how long to wash large quantities of rice and washing it for a certain period of time by hand is a lot of work. Also as the seimai-buai gets lower and lower, not only seimai gets more difficult but seimai as well. In the next article, we will introduce shinseki / mizukiri (soaking / straining)!

Ms.Suzuki, Kanbai Shuzo


If you have enjoyed this article and feel ready to embark on a voyage of discovery, why not head on over to Japan, to Tokyo, and visit KURAND where you can taste over 100 different types of sake without time limits at your own leisure. Each sake comes with a story of how it was made and no two sake are made 100% the same way. We look forward to welcoming you very soon!