Abstract To monitor lethal efficacy of pasteurization processes, an isolated extrinsic enzyme-based time–temperature integrator (TTI) was developed based on reaction enthalpy measurement of heat inactivation ofBacillus amyloliquefaciensα-amylase. After careful isothermal calibration and validation of the correct functioning of the system under variable temperature conditions, the TTI was applied as a wireless device to determine the influence of a process parameter (end-over-end rotational speed) on the spatial distribution of process lethalities in a particulated food model system, pasteurized in a water cascading retort.