Soybean commonly causes food allergy. Degradation of allergenic proteins to less than 10kD is known to reduce the allergenicity. We thus developed a novel fermentation method to degrade the allergenic proteins to amino acids and polypeptides of less than 10 kD.

Steamed soybeans were fermented with following microorganisms; Lactococcus lactis subsp. lactis, Aspergillus oryzae and Bacillus subtilis or various combinations of these microorganisms. Soybean proteins were extracted after fermentation and separated by SDS-PAGE. An antigenicity of the soybean protein was analyzed by immunoblotting method, using a soybean protein specific polyclonal antibody with the serum of a soybean-sensitive atopic dermatitis patient.

The soybean proteins were degraded to amino acids and peptides of less than 10kD molecular weight after the fermentation using all three microorganisms (three step fermentation). The antigenicity of the soybean protein was undetectable.

The data suggest that the three step fermentation method may reduce the allergenicity of the soybean by efficiently degrading the antigenic proteins in the soybean. This technique can also be applied to remove other allergens such as peanut allergens.