Shubo buai (yeast starter ratio)

Shubo buai (yeast starter ratio) is an indicator of how much of the total rice used in making a sake is used to prepare the shubo (yeast starter). Specifically, it is calculated by dividing the weight of rice used for the shubo by the total rice weight up to the final addition (tome), meaning the combined weight of all rice used in the brewing, not just the shubo, and then multiplying the result by 100. The higher the proportion of shubo, the more likely the sake is to be a high-quality type such as Ginjo or Daiginjo, with rich aroma and flavor. Shubo buai is regarded as one of the important indicators for evaluating the quality of sake.