Lactic acid bacteria (Nyusankin)

Lactic acid bacteria (nyusankin) is a general term for bacteria that break down carbohydrates and produce lactic acid. They play an important role in sake brewing, particularly in making kimoto-style shubo (yeast starter). In kimoto, lactic acid bacteria are cultivated in a natural environment, which keeps the shubo acidic and prevents the growth of unwanted bacteria. This creates an environment in which yeast can grow strongly. However, some bacteria in the lactic acid group, known as "hiochi-kin" (hiochi bacteria), are harmful and spoil sake. For this reason, it is important to pasteurize the sake (heat treatment, known as hi-ire) to kill these bacteria. In this way, lactic acid bacteria are microorganisms that are essential to protecting the quality of sake.