The Buildup – San-Dan-Jikomi – Transition from Moto to Moromi

A look at the process of building up a sake batch from the moto (yeast mash) to moromi (main ferment).

After the moto has completed, four days are taken to buildup the brew from moto to moromi. The four days are made up of three additions and a day of rest:

  • Hatsuzoe – the first addition, day 1
  • Odori – The dancing ferment, day 2, day of rest
  • Nakazoe – the second addition, day 3
  • Tomezoe – the third and final addition, day 4

I have also seen hatsuzoe called soe, nakazoe called naka and tomezoe called tome. However, my lack of Japanese limits my understanding of how these might correspond. Naka means inside or middle, as in the middle addition. Tome means stop or remaining, as in the last or final addition.

In each addition the amount of steamed rice, koji and water added are increased until it reaches full size after the third addition. At this point it is between about 8-16 times the size of the moto. With the first addition added the concentration of acids has been just about halved. This is significant because of the protection from wild yeast and bacteria it provides is now not nearly as strong. Similarly the concentration of yeast is around half what it was at the end of moto. Also, with the start of the additions the temperature of the ferment is lowered. Wild yeast and bacteria do not like the lower temperatures as much as do the sake yeast.

Day 2, Odori, provides the yeast with a chance to build their numbers back up to roughly the same concentration they had at the end of moto. During this day of rest for the mash, the yeast are both multiplying (the aerobic stage) and converting sugars to alcohol and carbon dioxide (the anaerobic stage). By the end of the day, yeast concentration has mostly recovered.

With the yeast back in strength, the middle and final additions are made on the next two successive days. The rice absorbs most of the liquids in the ferment and thickens into an almost solid mash. Over the next few days, first few days of moromi, the enzymes from the koji work on the rice starch dissolving it and releasing the liquids.

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