Kinetics of Available Lysine Loss During Thermal Processing of a Soy Protein Isolate: Reversion of No-Loss to Rapid-Loss Phase

Available lysine loss in soy protein isolates may change from a first-order loss to a no-loss phase depending upon processing conditions. The change in reaction kinetics occurs during thermal processing in the absence of shear and pressure. Soy isolate systems do not always exhibit the no-loss phase during extrusion. Thermal processing, a mixture of soy protein isolate and cellulose does not induce the no-loss phase. Once a protein, cellulose and glucose model food system has entered the no-loss phase, pressure in excess of 500 psi (3450 kPa) and shear rates greater than 1000 sec-1 will not revert the no-loss phase to the rapid-loss phase.