Close-Up of Sake Production: Rice Soaking

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

This is another article in the series taking a closer look at the sake production process. In this article we look at shinseki (rice soaking). Another rather menial sounding task but once again, nothing but could be further from the truth. As with every part of sake brewing, the soaking is an essential stage that requires skill, experience and precision.

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 plays a pivotal role in determining the end style and flavor, so it is definitely worthy of a more detailed explanation.

What is Shinseki?

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The purpose of soaking is to absorb water into the center of the rice grains. In a way it is very similar to the secondary aim of washing, and in some breweries, the soaking is carried out as a part of the washing process. The final moisture content is an essential prerequisite to making good koji. As with the washing, the length of soaking and water temperature are carefully controlled. The process can last anywhere from a few minutes to a few hours. Even experienced brewers conduct this step with caution.

How Does Soaking Affect Sake?

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The length of shinseki changes depending on the type of rice and rice polishing ratio. If the rice is left in for too long, the rice will absorb too much water. Rice that absorbs too much water will not have the correct consistency after steaming. And this will have a negative effect on all the brewing steps that follow.

Higher polished rice is soaked for a much shorter time because it is more porous and thus absorbs water at a much faster rate. A special technique called gentei-kyusui (limited water absorption) is sometimes used to purposefully restrict the soaking time and control it more accurately. However, if the restriction is too extreme the rice will not absorb enough water and results in something called namabuke, where the rice core is still hard, even at the end of steaming. Once again, in most cases, it is the toji’s responsibility to ensure that the rice absorbs the perfect amount of moisture.

Asking Brewers About the Difficulty of Shinseki

Determining the length of time for soaking is probably the most difficult part, because it all comes down to super precise temperature control. Just a degree of difference can greatly alter the length of soaking. Things never go according to the textbook so every year is a challenge.
(Wakamatsu-san, Takarayama brewery)

The length of soaking is timed by a stopwatch and when the time comes I need to immediately lift the full strainer out of the water. The rice is full of water making it difficult to lift because it is so heavy.
(Hasegawa-san, Hasegawa brewery)


So there you have it, nothing in brewing is as easy as it sounds. And the process only gets harder from here on. In the next article we will look at how the brewer strains the water from the rice. 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!