Development of β-conglycinin quantitative method in soybean foods using capillary electrophoresis-based immunoassay

beta -Conglycinin ( beta -CG), a major soy protein, has been associated with the reduction of body fat and triglycerides in the blood. Quantitation of the alpha , alpha' , and beta subunits in beta -CG is desirable to establish the functional properties of beta -CG in soybean. Therefore, in this study, we used the Jess System, a capillary electrophoresis-based immunoassay system, for quantifying beta -CG in soybean foods. The validity of this method was confirmed using soybeans and processed soy milk. The within-laboratory reproducibility of the total beta -CG amount was < 15 %, and its trueness was > 80 %. The beta -CG content in the commercially available soybeans, Kori -tofu, soy milk, soy yogurt, Okara powder, and soy meat was determined to be 40.3-148.5, 65.2-97.2, 6.1-7.8, 3.5, 18.0, and 57.5 mg/g, respectively. For the first time in the literature, this method enables the quantitation of individual subunits of beta -CG, despite the large variation in the amount of each subunit.