February 06, 2018

07/02/2018: A lesson in the processing technology of Japanese sake

by Satake

Sake rice (preferred rice for brewing sake) has external characteristics such as larger grain than regular short grain rice, larger Shinpaku (opaque area) at its belly, and a shallower surface groove
 


Internally it has lower protein and fat contents, with better water absorption to dissolve rice malt. Moreover, its hard surface and soft endosperm is ideal for sake brewing. A variety named Yamada-Nishiki, which is grown in Hyogo prefecture well, matches these characteristics and is quite popular all over Japan.

Occasionally, a variety is selected from normal non-sake rice and used in combination with sake rice.

Milling and milling degree
Different types of sake require different milling degrees of sake rice, and different milling degrees require different milling technology. Sake rice millers show their experiences and skills for optimum milling, remove fat from embryo without cracking rice, regardless of variety of rice which affect grain hardness.

Satake offers dedicated control software including various milling patterns according to rice varieties and required milling degree.

Cooling and washing rice

After milling, rice is cooled down to ambient temperature. This process is necessary to avoid cracking rice grains in the washing process that follows to remove fine bran on the surface. Generally, temperature of washing water is less than 10°C, and around 5°C is preferred for Ginjo sake. The washing process drains approximate 30-40 percent of potassium, 20 percent of phosphoric acid, little amount of sodium, magnesium, sugar, protein, amino acid and fat from rice. Washing water quality is important so that rice should not absorb calcium and iron from the water.

Soaking rice

The purpose of soaking rice in water is to absorb water into the core of grains. It enables heat to spread around the surface of grains equally during steam heating. It is required to adjust the soaking period according to rice quality, water temperature, and milling degree. Experience and skill of the brewers are needed.

Steaming rice
Steaming the rice after soaking will sterilise and pregelatinise the rice. The optimum steam cooking makes rice grains separate easily, hard on surface and soft inside, and less sticky on the surface, which is essential to make the saccharification process easier.

Cultivation of aspergilli The next procedure is to inoculate pores of aspergilli into steamed rice to cultivate it.

The dedicated cultivation room is air and humidity-controlled. On the flat bed, there are wooden boxes with aerators. The temperature is controlled from the lower part.

Steamed rice is spread and flattened evenly on the bed. Temperature of the rice is controlled at around 35°C and malt is sprinkled on it.

After the process makes the rice temperature rise by 2-3°C by the malt, brewers break up rice into grains and mix in the air-conditioned room.

Air temperatures and rice layer thickness are changed in different stages. In total, it takes approximately 48-50 hours to cultivate Shubo malt and 43-45 hours for rice malt. Shubo malt is one of the ingredients of Shubo. To make it, they culture aspergilli on steamed rice (= rice malt). Then, they add steamed rice and water to make rice glycated. Finally yeast is cultivated.


Read the full article with figures, HERE.

Visit the Satake website, HERE.
 

The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine Milling and Grain
which is published by Perendale Publishers Limited.


For additional daily news from milling around the world: global-milling.com

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