Thermal Inactivation of Soybean Bioactive Proteins

Abstract

Inactivation of trypsin inhibitor, lipoxygenase 1, and urease during the processes of dry extrusion, wet extrusion, micronisation, microwave roasting and autoclaving were studied. Cultivars Bosa, ZPS 015, Goyou Kurakake and L93-7290 were used in the experiment. Depending on a technological procedure of processing, kernels were exposed to temperatures from 57 to 150 oC for different time: from 25-30 sec in the process of dry and wet extrusion, to 30 min in autoclaving. The process of dry extrusion had the greatest influence on reduction of the trypsin inhibitor content and inactivation of urease and lipoxygenase 1. During the dry extrusion at 100 oC trypsin inhibitor declined by 74.2 % and the residual activity of a lipoxygenase 1 and urease was only 0.76 i.e. 0.55 %, respectively. Lipoxygenase 1 was the most heat labile enzyme, followed by urease and than trypsin inhibitor.