Relationship between peroxyl radical scavenging capability measured by the chemiluminescence method and an aminocarbonyl reaction product in soy sauce.

Oxygen-related free radicals have been suggested as a cause of aging and various diseases, for example, various cancers and rheumatoid arthritis. Because of this a radical scavenger as an antioxidant has been sought in food materials. Soy sauce is a traditional fermented seasoning of East Asian countries and is available throughout the world. The relationship between the peroxyl radical scavenging capability using the luminol chemiluminescence method and melanoidin, the main product from aminocarbonylation, i.e., Maillard reaction, from soy sauce was examined. In this study, we report that soy sauce has a very high antioxidative capacity and from the comparisons of the IC50 values of 26 soy sauces in the case of the optical density of the soy sauce's color being standardized, it was found that not only melanoidin is an antioxidative product, but also other products have strong antioxidative properties.