Bodaimoto (traditional water-based yeast-starter method)

Bodaimoto is a type of kimoto-family shubo (yeast starter) and a sake-brewing method that originated around the 14th century at Shoryakuji Temple on Mount Bodai (Bodaisan) in Nara Prefecture. The technique was devised to make the shubo safely, even in the summer months. Bodaimoto is also called "mizumoto" (water starter). Polished rice is soaked in water, and cooked rice is buried in it, which produces lactic acid. This lactic acid suppresses the growth of unwanted microbes, so brewing can be carried out with confidence even in warm seasons. The bodaimoto method was also famous in the Nara period through a renowned sake called "Bodaisen," and many documents record that this sake was made in the 1440s. Because Bodaisen was made by single-stage brewing (ichidan-gake method), it is regarded as the shubo of the modern era in itself, and it is praised as an extremely clever and rational method from a microbiological standpoint. Specifically, about 10 percent of the rice to be used is cooked, and this cooked rice is buried in the remaining 90 percent of the rice, which is soaking in water. Nutrients dissolved out of the cooked rice encourage the growth of lactic acid bacteria. The acidic water produced by the resulting lactic acid, also known as "kusaremoto," is then used as the brewing water, which effectively suppresses the growth of unwanted microbes. Today, some breweries still make sake with bodaimoto, and the traditional method has been passed down. In this way, bodaimoto is an important technique that, together with its historical background, continues to influence modern sake brewing.