Nitrite (Ashosan)

Nitrite is an important compound in sake brewing, and its presence has two sides. In the production of kimoto-style shubo (yeast starter), nitrate is reduced by nitrate-reducing bacteria, generating nitrite. This nitrite helps suppress hayawaki (premature fermentation by the yeast), so it has a certain significance in the brewing process. In general, however, a high nitrite concentration in water often signals bacterial contamination and may adversely affect brewing, so managing it is very important. Handling nitrite with an appropriate balance is therefore essential to maintaining good sake quality.