Heat inactivation of trypsin inhibitors in soymilk at ultra-high temperatures

Soymilk samples at pH 7.5, 6.5 and 2 were subjected to heat treatment at 93 degrees C and indirect ultra-high temperature. When heated at 93 degrees C, 121 degrees C and 132 degrees C, trypsin inhibitor activity (TIA) in soymilk was more heat-labile at high pH than at lower pH. However, the effect of pH on rate of thermal inactivation was less pronounced when the holding temperature was increased to 143 degrees C and 154 degrees C. The point on a curve relating holding temperature and holding time, indicating inactivation of 90% of the TIA in soymilk at pH 6.5 in the range 93-154 degrees C, coincided with the thermal-death-time curve of the organism putrefactive anaerobe 3679 at about 125 degrees C