Hydrolysis (kasuibunkai)

Hydrolysis is a reaction in which an inorganic or organic substance is broken down by reacting with water. In this process, water molecules take part in the reaction and cleave chemical bonds, producing new compounds. In sake brewing, hydrolysis occurs in particular when enzymes in koji, known as alpha-amylase, break down the starch in rice. The sugars produced by this reaction are converted into alcohol by yeast during the later fermentation process, making this an important step in the transformation of rice into sake.