Inactivation kinetics of immobilized bovine pancreas trypsin (type III) was used in conjunction with a finite difference model to verify fluid-to-particle heat transfer coefficients to particulates in a holding tube of a pilot scale aseptic processing simulator operated at temperatures ranging from 90 and 110 degrees C. The enzyme was sealed in a stainless steel capsule, which was pretested to be suitable for high-temperature, short-time applications, and embedded at the center of a finite cylindrical particle. The percentage retention of the enzyme activity was calculated by using transient temperatures and their respective D values in a finite difference program. Heat transfer coefficients estimated for the potato particles under similar experimental conditions were used as input data. Excellent comparison was observed between predicted and measured percentage retention of enzyme activity.