Removal and recovery of antinutritional factors from soybean flour

An integrated process for removal purification of two antinutritional factors, namely soybean trypsin inhibitor and soybean agglutinin, from soybean flour has been developed. The process is based upon binding of soybean trypsin inhibitor and soybean agglutinin to an immobilized metal affinity chromatography medium, consisting of zinc alginate beads. Both soybean trypsin inhibitor (95%) and soybean agglutinin (94%) could be removed from an aqueous extract of soybean flour. The bound protease inhibitor and lectin could be recovered by washing the zinc alginate beads with 0.05 M imidazole solution and dissolving the beads in 0.01M EDTA, respectively. Recoveries of 89%, in the case of soybean trypsin inhibitor and 81% in case of soybean agglutinin, were possible. Both purified proteins gave single band on SDS–PAGE. Thus, soybean flour, free of these two antinutritional factors, could be obtained. Simultaneously, these two antinutritional factors were purified as value-added products.