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Making sake: washing, soaking, and steaming the rice

 

Once polishing is completed, the rice is washed to remove any remaining particles of bran on the surface of the grains. This step is called senmai.

 

After washing, the rice is soaked so that it absorbs water. This procedure is called shinseki. After these two steps are completed, the rice is steamed.

 

Washing and soaking
Sake can not be made by merely going on one's instincts. Good sake results from following procedures according to established calculations. Before the rice is steamed, there are two important steps that raise the moisture content of the rice: washing (senmai) and soaking (shinseki).

 

In making sake, washing the rice (senmai) is quite a different sort of procedure from washing rice before steaming it for a meal. The rice used in making sake has been highly polished and, as a result, is quite fragile and delicate. Great care needs to be taken in washing it.

 

Furthermore, because of their polished surface, the rice grains absorb moisture very easily, so it is essential to complete the washing rapidly. Washing must take no longer than absolutely necessary. If the timing is wrong, the rice will become sticky and it can no longer be used.

 

It is the same with the next step, soaking. The rice must not be allowed to soak for longer than necessary. Soaking must be stopped when the rate of absorption reaches 80%.

 

Because such precision is required, the times allowed for washing and soaking are measured in terms of seconds. These processes are measured with a stopwatch and stopped when water absorption reaches a critical level. When these processes are done by hand, the weight of the rice must be accurate to within 0.2%.

 

Another issue is that the water absorption properties of the rice vary depending on the variety of rice used. And even with the same variety of rice, water absorption depends on the rice polishing ratio (the index that indicates how much of the outer layers of the rice is polished off). The region in which the rice was grown and the kōbo (yeast) used to ferment the sake are other factors that need to be considered in adjusting the timing of procedures. Many years of experience and the accumulation of data mean that the optimum length of time for washing and soaking can be determined to within a few seconds.

 

Nowadays, washing is done by machine at most breweries. However, in the case of ginjō-shu production, where a large proportion of the rice grain has been removed by polishing, washing is still sometimes done by hand.

 

Steaming
Normally, rice cooked for a meal is boiled, but the rice used for making sake needs to be steamed. Naturally, there is a reason for that.

 

First of all, the rice needs to become soft. The rice will be mixed with kōji-kin (the mold used to prepare a kōji culture that will convert rice starch to fermentable sugars) and it must be soft so that the kōji-kin can easily penetrate it. This softening is referred to as the “gelatinization of the rice starch.” In addition, the steaming serves to sterilize the rice, making the subsequent steps in the brewing process easier.

 

The rice is steamed in a large vat called a koshiki. In the past, the koshiki was usually made of wood, but nowadays stainless steel is generally preferred as it is easier to wash and sterilize.

 

Rice is steamed in the koshiki for around 45–60 minutes. At the end of this period, the steamed rice can be seen when the lid is removed.

 

The steamed rice is separated into two portions: one for making kōji and another to be used as the raw material for the brew. The latter portion is used for various purposes, including the yeast starter (shubo) as well as for additions to the mixture. The steamed rice is an ingredient that is used in various ways.

 

One important point to bear in mind is that the ideal temperature of the rice will depend upon whether it is to be used for making kōji, or for the yeast starter (shubo). In any case, the steamed rice has to be removed from the koshiki. It may be transferred to a rice-cooling machine or it may be spread out and allowed to cool naturally. The temperature to which the rice is cooled depends on the use to which the rice will be put.

 

For these reasons, it is considered that better steamed rice can be made using a koshiki than with a steaming machine.

 

Partly because of this, the majority of breweries use a koshiki for steaming rice for the crucial procedure of making kōji. In particular, in making fine, high-grade sake such as ginjō-shu, steaming rice with a koshiki is generally the preferred method.

 

This is how the steamed rice for making sake is produced. By observing whether a brewery uses a machine in the process or not, one can get an idea of grade of the sake produced there.


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