One Final Calculation for Good Koji: Dekoji

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

Following our recent Closeup of Production series, over the last few articles, we will be zooming into the various steps of the process and offering even more insight into how they are carried out. In this series, we look at koji making/seigiku. This is the last article in the series on koji making. We will take a closer look at the final stage called dekoji.

As a supplement to the recent Closeup of Production series, over the next few articles, we will be zooming into the various steps of the process and offering even more insight into how they are carried out. In this series, we look at koji making/seigiku. This is the last article in the series on koji making. We will take a closer look at the final stage called dekoji.

Glossary

Koji = steamed rice with mold growing on it
Koji mold = the mold used to make koji
Seigiku = process of making koji
Haze = pronounced ha-ze describes the mold growth
Haze-guai = the state of haze
Kirikaeshi = breaking up, the second stage in koji making
Koji-muro = koji room
Koji-kin = Japanese word for koji mold
Shimpaku = starch filled core in the center of rice grain
Mori = mounding
 

What is dekoji?


After shimai-shigoto, when the koji-mai reaches the appropriate temperature, it is taken out of the koji-muro to cool and dry. This process is called dekoji. The final judgement of when to take the koji out is normally made by the kojiya or toji, because it is an extremely important one and requires experience and skill. The timing of dekoji varies depending on whether the koji is intended for the moromi (fermentation mash) or shubo (fermentation starter). Generally, a koji with more mold growth is preferred for the shubo because the yeast needs nutrients (a fast breakdown of starch) to grow healthily.

The actual purpose of dekoji (literally, taking koji out) is to completely halt the activity of the koji mold by lowering the temperature of the steamed rice and letting the moisture evaporate. Heating the koji up would also halt its activity but it would also kill it releasing unwanted aromas and flavours into the final product and rendering it useless. If it cools down while still moist, it provides the perfect breeding ground for bacteria that can disrupt the delicate balance of acidity resulting in a lower quality koji—and poor quality koji is the recipe for poor quality sake. The brewer prevents moisture from forming before the temperature drops by cooling and drying simultaneously. It is a task which requires focus and attention until the very end.

Timing is Key


For the traditionally made futa-koji and the box-koji the koji-mai is transferred into larger wooden boxes or the big tables called toko and wrapped in cloth to help ventilate it, before being carried from the koji-muro to a space called the karashiba where the koji is left to cool. In some breweries with smaller koji-muro, this task is incredibly labor intensive because the tables or toko have to be continually switched around. Most breweries have their tables on casters but even so the tables are quite heavy and pushing them in and out of the koji-muro switching from a tropical climate to a freezing cold one is exhausting work. Koji that is dried enough during dekoji at the karashiba is used for making shubo and moromi.


That about sums up the whole process from tokomomi to dekoji. This is the whole process of seikiku. Defining characteristics of this process is that the water level and temperature of the rice must be managed very carefully and focused / precision are required until the very end.
The devotion and skill of the craftsmen is the recipe for delicious sake.
Knowing about sake undoubtedly makes the sake taste better. Understanding how sake is made can lead to new discoveries when you taste it! And there is no better place to do that than KURAND in Tokyo. We have branches all over Tokyo and for just one flat fee, you can taste as little or as much as you want, pairing with food, with no time limits. We look forward to welcoming you soon.