A small sized single-component enzymatic time temperature integrator (TTI) was developed. It consisted of glass beads coated with Bacillus licheniformis alpha-amylase (BLA) and stabilizing additives in a dehydrated form. Post heating residual enzymatic activity was used as a response property of the TTI. Under isothermal conditions, different batches of the system were characterized by Z(TTI)-values around 13.5degreesC in the temperature range 100-130degreesC as well as by their ability to provide a response within 5 min after thermal processing. When used under non-isothermal conditions in a model food (silicone spheres), the system allowed to measure process-values F-zTTI(121.1degreesC) UP to 60 min with an average error of 10.9%. The capabilities of the system were validated in a real solid/liquid food matrix sterilized by retorting. The combination of F-TTI-values with heat transfer simulations based on finite difference calculations allowed for the determination of process values, which evaluated actual process-values F-10degreesC(121.1degreesC) up to 90 min with an average error of 11.4%. The good performances of the system as well as its easiness of preparation and use, make the latter a valuable biological device for thermal process assessment. (C) 2004 Wiley Periodicals, Inc.