Degradation of Soybean Allergens during the Process of Low-salt Solid Soy Sauce

This study explored the degradation of soy allergen in the process of low-salt solid soy sauce brewing. Based on the establishment of a simulated low-salt solid soy sauce brewing laboratory,the samples of untreated soybean,autoclaved(121 ℃,8 min),koji-making stage(44 h),fermentation stage(30 d),pre-sterilization and sterile zation were taken. The composition of proteins in the brewing process was measured by polyacrylamide gel electrophoresis,and rabbit anti-soy polyclonal antibodies were used to perform enzyme-linked immunoassay and immunoblot experiments to analyze the changes in soybean allergen antigenicity during fermentation. SDS-PAGE results reflected that after autoclaved,koji,fermentation and heat sterilization,the soy protein bands in the raw materials decreased or disappeared and the variation of the koji was the largest in the four stage. The α and α' subunits of β-conglycinin and acidic subunits of glycinin begin to degrade during the koji making stage,the β subunit of β-conglycinin and glycinin acidic subunits disappeared after the koji,the basic subunits of glycinin did not change much throughout the brewing stage. The results of immunoblotting showed the similar results. The allergenicity and antigenicity of soybean allergens gradually decreased during the brewing process. After 30 days of fermentation,glycinin can still be detected in raw soy sauce,and was not completely degraded after sterilization,but these residual soybean allergens did not detect IgE binding capacity. The results of enzyme-linked immunosorbent assay showed that,compared with the raw material soybean,the antigenicity in the sample decreased by 8.13%,39.00%,69.10%,and 87.06% after high-pressure cooking,koji making,fermentation,and heat sterilization,respectively. The allergenicity decreased by 8.92%,71.66%,92.26%,and 98.45%,respectively. Soybean allergens gradually degraded during the soy sauce brewing process,the koji-forming stage had the greatest impact on the degradation of soybean allergens,Glycinin remained in the soy sauce,but the sensitization of the residual protein was not detected.