SHUBO - MOTO

The fermentation starter

Prior to fermenting an entire tank of sake, a smaller starter batch “Shubo” is assembled from koji, freshly steamed rice, yeast, water and lactic acid. The purpose of a moto is to create a highly-concentrated population of specific yeast cells critical to a successful fermentation. Depending on the style and temperature of the starter (Kimoto, Yamahai, Sokujo, Ko-on-toka) moto/shubo development may take one week to one month before the required yeast concentrations and acidity are achieved.  

To prevent undesirable bacteria from out-competing a selected yeast strain, lactic acid is naturally propagated or added to the moto along side the developing yeast. Koji’s function in the moto is to break down rice carbohydrates to provide a stream of glucose and nutrients which support yeast health and the resulting production of ethanol alcohol.