This contribution investigates the impact of different thermal boundary and initial conditions on the homogeneity of enzyme inactivation during a short-time high-pressure (STHP) process (pressure ramp 400 MPa/s; holding time 120 s; pressure 700 MPa). Enzymes with different pressure- and temperature-sensitivity (beta-glucanase, alpha-amylase, lipoxygenase, polyphenoloxidase) are chosen to examine the extent of the impact of thermofluiddynamical inhomogeneities on the final process result. Water serves as the process medium. Velocity, temperature and enzyme activity fields in the treatment chamber are determined by numerical simulation. Depending on the parameter constellation, remarkable inhomogeneities in enzyme concentration develop during the process. By characteristic time scales with consideration of boundary and initial conditions, thermal and conversion uniformity of the process can be estimated. (C) 2008 Elsevier Ltd. All rights reserved.