The Kimoto brewing method dates back to the 17th century. For hundreds of years, it was the only method used. In the early 1900’s, two other methods came to fruition: Yamahai and Sokujo-moto (quick fermentation).
The labor-intensive Kimoto method begins with the creation of moto, or shubo – the yeast starter mash. Over several days, water, rice and koji are thoroughly mixed in a small vat using a ‘pole-ramming’ technique: pole-like tools, with blunted blocks at the end, mix and smash the ingredients into a paste-like consistency. This mixing with poles is one of the defining aspects of the Kimoto method.
Next, a series of chemical developments occur, the most important of which is the creation of lactic acid. This lactic acid kills almost all bacteria and wild yeast in the tank, while allowing the sake yeast to thrive (it protects the sake yeast from being depopulated by the wild yeast). The Kimoto method produces a more complex sake with longer flavors.