Reducing Sugar
Reducing sugar
Japanese: 還元糖（かんげんとう）
Amount of sugars involved in Maillard reactions. Indicator related to miso color and aroma changes.
Reducing sugars have aldehyde or ketone groups that participate in Maillard reactions. In miso, glucose and maltose are representative, generated by koji amylase breaking down starch.
More reducing sugars drive more active Maillard reactions, darkening miso color and creating complex aromas (melanoidins). White miso stops aging while reducing sugars are abundant (staying sweet); red miso's deep color results from advanced Maillard reactions. Sugar quantity directly designs color.
Reducing sugars are measured using Somogyi-Nelson or DNS methods. Tracking reducing sugar changes during maturation predicts the degree of Maillard reaction progression. Controlling this component, which affects both color and sweetness, is key to achieving the targeted miso flavor profile.