Unique Clear, reddish-Brown Color
The superb color unique to soy sauce is the result of the “Maillard Reaction,” which begins two or three months after brewing starts. In this reaction, glucose and other sugars combine with amino acids to produce a brown pigment called melanoidin, which gives soy sauce its beautiful color.
Soy sauce grows darker owing to oxidization when it comes in contact with air. Storage at lower temperatures inhibits this color deterioration, and so we recommend that you store Kikkoman Soy Sauce in the refrigerator once the bottle has been opened.