BIOLOGICALLY-ACTIVE COMPONENTS INACTIVATION AND PROTEIN INSOLUBILIZATION DURING HEAT PROCESSING OF SOYBEANS

Inactivation of lipoxygenase, trypsin inhibitor, urease and retention of protein solubility during water blanching of dehulled soybeans at 90 degrees, 95 degrees and 100 degrees C were investigated. Lipoxygenase was the most heat labile, followed by urease and then trypsin inhibitor. Processing time based on ''acceptable inactivation time'' (AI) was proposed. AI value was longest for trypsin inhibitor, followed by urease and then lipoxygenase. The combined effect of heat on protein solubility and biologically active components inactivation was expressed as ''PDI at acceptable inactivation time'' (PDIAI). PDIAI value for the processing ''limiting factor,'' trypsin inhibitor inactivation, at the three temperatures were 36.7%, 42.5%, and 34.8%, respectively.