Effect of extrusion on the structure and antigenicity of soybean β-conglycinin

Abstract

Abstract β-Conglycinin, the main component of 7S globulin in soybean protein, is also a key soybean antigen protein that causes allergic reactions. Extrusion technologies have received considerable attention as a method for modifying soybean protein allergens. This study investigated the changes in β-conglycinin structure and antigenicity upon extrusion. Isoelectric precipitation, ammonium sulfate precipitation, and sepharose CL-6B gel filtration were used to isolate and purify β-conglycinin from soybean powder, and single-factor and orthogonal tests were used to study the effects of water content, extrusion temperature, screw rotation speed, and feeding speed on the antigenicity of β-conglycinin after extrusion. Fourier transform infrared spectrometry (FTIR) was then employed to analyze the structure of β-conglycinin after extrusion under the optimal conditions determined by the orthogonal test. The results showed that extrusion significantly reduced the antigenicity of β-conglycinin (P feeding speed > screw rotation speed > water content. The optimal conditions were temperature at 130 °C, screw rotation speed at 140 r/min, and feeding speed at 35 g/min. Under these conditions, the contents of α-helix, β-pleated sheet, and β-turn structures in β-conglycinin were significantly reduced (P