Potassium nitrate

Potassium nitrate (KNO3) is a chemically important compound best known for its use as a fertilizer. In sake brewing, its properties are sometimes put to use, particularly when preparing shubo (yeast starter) in the kimoto family of methods. Kimoto-style shubo is a traditional fermentation method that relies on naturally occurring yeast and lactic acid bacteria, and temperature control and fermentation stability are important. Adding potassium nitrate to the water used to prepare the shubo is expected to prevent early fermentation activity (hayawaki, premature bubbling) and to improve the stability of fermentation. However, potassium nitrate must be used with care, and the appropriate amount and timing are required.