Effect of processing on soybean allergens and their allergenicity

Soybean is the largest source of protein meal worldwide but is an allergen affecting 0.5% of the general population. Soybean contains at least 30 allergens, such as Gly m 1 to Gly m 8, P28 and P34. Soybean allergies can cause allergic symptoms such as asthma, shock and death. Thus, identifying soybean allergens and reducing allergenicity are crucial for solving the problem of soybean allergies. This review summarized the characteristics, structures and epitopes of soybean allergens, especially major allergens (Gly m 4, Gly m 5, Gly m 6, P28 and P34). Various processing techniques to reduce the allergenicity of soybeans were evaluated and compared, including thermal processing, fermentation, high hydrostatic pressure, sprouting, enzyme catalysis, glycosylation and irradiation, etc. Characteristics, structures and epitopes of soybean allergens play important roles in soybean allergenicity. Among the various methods to reduce soybean allergenicity, thermal processing, enzymatic degradation and fermentation are effective in reducing the allergenicity of soybean, resulting for the destruction of epitopes and the reduction of allergens mainly induced by protein degradation. In addition, fermentation strains and metabolites reduce the sensitivity of the body to allergens. Using irradiation to reduce the allergenicity of soybean at safe dosages (≤10 kGy) is difficult. Other processes (e.g., high hydrostatic pressure, glycosylation and sprouting) may work under certain circumstances. A combination of multiple methods is a potential novel method to reduce the allergenicity of soybean.