DETECTION OF SOYBEAN ANTIGENICITY AND REDUCTION BY TWIN-SCREW EXTRUSION

Antiserum toward soybean meal was prepared by feeding a soybean meal d iet containing large amounts of antigens to calves. The antiserum was used to develop a sensitive detection method for soybean meal antigens by competitive inhibition enzyme-linked immunosorbent assay. With thi s method, the effectiveness of twin screw extrusion cooking in reducin g antigenicity in soybean meal was examined. Antigenicity was reduced to 0.1% of the original activity by extrusion cooking with screws cont aining kneading-disc elements and die-end temperatures exceeding 66 de grees C. Electrophoretic analysis of the cooked meal indicated that th e reduction in antigenicity was due to degradation of protein structur es, particularly those with molecular weights exceeding 40 kDa.