Development characterization and use of a high‐performance enzymatic time‐temperature integrator for the control of sterilization process' impacts

A small sized single‐component enzymatic time temperature integrator (TTI) was developed. It consisted of glass beads coated with Bacillus licheniformis α‐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 13.5°C in the temperature range 100‐130°C 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 zTTI F 121.1°C 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 10°C F 121.1°C 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. © 2004 Wiley Periodicals, Inc.