Soy sauce is a traditional fermented seasoning of East Asian countries and is available throughout the world. Wheat and soybeans are the 2 main raw materials of soy sauce, and soy sauce also contains a high concentration of
salt. Since
wheat allergy is considered a serious problem globally, it is significant to examine the allergenicity of soy sauce. In this study, by immunoblotting, inhibition ELISA and direct ELISA using sera from 5 children with
wheat allergy, it was clearly demonstrated that wheat
allergens were degraded into
amino acids and
peptides losing the
IgE-binding ability in both
salt-soluble and
salt-insoluble fractions of soy sauce during fermentation. Furthermore, no wheat
allergen was detected in 10 items of commercial soy sauce in Japan, by inhibition ELISA or direct ELISA using the sera of patients. In the brewing process of soy sauce, first
salt-insoluble wheat
allergen was solubilized to
salt water during the koji stage (mold cultivation and
enzyme production), and second both the resultant
salt-solubilized and initially
salt-soluble wheat
allergens were completely degraded during the moromi stage (fermentation) by microbial
proteolytic enzymes. Therefore, it was concluded that no wheat
allergen is contained in soy sauce.