Kimoto (traditional yeast-starter method)

Kimoto (生もと) is one of the traditional methods of making shubo (yeast starter). It uses koji, steamed rice, and water, and the ingredients are ground down by hand in a process called yamaoroshi (also known as moto-suri). This work encourages the growth of naturally occurring nitrate-reducing bacteria and lactic acid bacteria, which suppress the growth of unwanted microbes while a large quantity of pure, high-quality yeast needed for alcoholic fermentation is cultivated. Kimoto takes about 30 days to complete and demands considerable labor and time, but it is an important process for producing sake with depth of flavor. More recently, a simplified method of making shubo called yamahai-moto (yamahai) has appeared. Because it allows the shubo to be prepared in a shorter time than traditional kimoto, many breweries use it. Newer methods such as standard sokujo shubo (quick-method yeast starter) and high-temperature saccharification shubo have also become widespread, allowing sake to be made efficiently. Even so, kimoto is still valued at many sake breweries for its distinctive flavor and character.