Oxidation induced by dielectric-barrier discharge (DBD) plasma treatment reduces soybean agglutinin activity.

In this study, potential of dielectric-barrier discharge (DBD) plasma treatment (40 kV, 12 kHz at 1, 2, 3 and 4 min) to eliminate soybean agglutinin (SBA) activity was investigated in a SBA model system and soymilk. The plasma treatment decreased the SBA in the model system and hemagglutination activity was decreased by 87.31%. SDS-PAGE analysis confirmed the degradation of the SBA polypeptide chain. The multi-spectroscopic analysis revealed a two-stage structure alteration in the SBA upon exposure to the plasma treatment. Oxidation of NH-/NH2- at the peptide bond disrupted the hydrogen bonds and altered the secondary structure of SBA. Further oxidation of aromatic amino acid, cleavage of peptide bonds and the breakage of polypeptide led to the SBA fragmentation and complete unfolding of the protein. The SBA inactivation by the plasma treatment was confirmed in soymilk. Plasma treatment is a promising technology for the elimination of SBA in soybean product.