Soy protein products are widely used as high nutrient sources in many food industries. However, allergenic proteins make it as one of the "big 8" foods. The objective was to analyze the molecular size, changes in protein structure and immunoreactivity of ethanol extracted soy protein concentrate in comparison with other major commercial soybean protein products extracted at different pH, and allergen stability after pepsin hydrolysis. The results showed that immunoreactivity of defatted soy white flakes (SPC2) was 227.7 mg IgE/kg protein or 102.4 mg IgE/kg product based on enzyme-linked immunosorbent assay (ELISA), the highest compared with other soy products; soy protein isolate (SPI) was the lowest (76.7 mg IgE/kg protein). Solubility of most allergenic proteins was higher at pH 12 than at pH 8.2, and the lowest at pH 2, especially no beta-conglycinin was extracted at pH 2. These results contribute to the understanding of the mechanism of immunoreactivity reduction in Soycomil and demonstrate competitive advantages compared to other soy protein products.