Degradation and removal of soybean allergen in Japanese soy sauce

Soy sauce is a traditional fermented seasoning of Japan and is available throughout the world. The two main raw ingredients of soy sauce are soybean and wheat, both of which are established food allergens. The present study examined the degradation and removal of soybean allergens in soy sauce by immunoblotting with anti-soybean protein antibody from rabbit and sera from two children with soybean allergy. It was demonstrated that soybean allergens were gradually degraded during the fermentation process, but were not completely degraded in raw soy sauce. During the processes of heat-treatment and filtration, the soluble soybean allergens in raw soy sauce were denatured to insoluble allergens by heat-treatment and subsequently completely removed from soy sauce by filtration. Therefore, to reduce the allergenicity of soy sauce, heat-treatment and filtration are very important processes in addition to the enzymatic degradation during the fermentation of soy sauce.