The effect of thermal treatment of whole soybean flour on the conversion of isoflavones and inactivation of trypsin inhibitors.

The aim of this paper was to evaluate the effect of the thermal treatment of whole soybean flour (WSF) on the conversion of isoflavones and the inactivation of trypsin inhibitors. Soybeans were ground and whole soybean flour was obtained and subjected to heat treatment in an oven for 10, 15 and 20min at 100, 150 and 200°C according to a 3(2) experimental design. The response functions were taken to be the contents of different isoflavone forms and the residual activity of trypsin inhibitors. The thermal treatment in the oven altered the content and profile of the different isoflavones forms. At 200°C for 20min, there was a higher conversion of malonylglycosides to acetylglycosides, β-glycosides and aglycones and a significant reduction in the activity of trypsin inhibitors. Mathematical models were established to estimate the process parameters in obtaining the WSF with isoflavone conversions and reductions in trypsin inhibitor activity.