Catalyst (shokubai)

A catalyst is a substance that promotes the reaction of other substances in a chemical reaction without itself being changed. In sake brewing, enzymes play an important role as catalysts. These include amylase, the enzyme that converts rice starch into sugar, and the enzymes contained in the yeast starter (醸母, jobo) that convert sugar into alcohol. By speeding up these reactions, the enzymes help the fermentation process proceed smoothly and contribute greatly to the final flavor and aroma. The presence of catalysts makes the sake brewing process efficient and effective.