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The method kimoto was used during the Edo period. It involves crushing the rice when creating the shu-bo, to allow and help the koji to transform the starch into sugar. This process is called yama-oroshi. At that time, the polishing rate did not exceed 90%, and no one knew how to select the yeasts. It is therefore indigenous yeasts that allow the transformation of sugar into alcohol. Lactic acid is produced naturally, allowing a natural selection of resistant yeasts and protecting the fermenting juice from bacteria
This technique is only useful in the case of brown rice that has been polished around 80% to 90% (% of rice remaining after polishing).
When the rice is polished above this level, it is no longer necessary to crush the rice to allow the koji to convert the starch into sugar. Today, legislation allows the use of pure slected yeast for Method Kimoto.