A sterilisation Time-Temperature Integrator based on amylase from the hyperthermophilic organism Pyrococcus furiosus

A candidate Time-Temperature Integrator (TTI) which is potentially suitable for use in validation of sterilisation processes was identified and tested. The TTI was based on the highly thermostable amylase produced from the extracellular medium of a Pyrococcus furiosus fermentation: this organism grows at temperatures in the region of 100 degrees C. Kinetic properties for the amylase following inactivation by heat showed it to be suitable for use as a sterilisation TTI. Isothermal kinetic data at 121 degrees C and non-isothermal kinetic data over the range 121 to 131 degrees C were determined. A decimal reduction time (D-T-value) at 121 degrees C of 24 min was calculated from isothermal tests and a range from 18.1 to 23.9 min from non-isothermal tests. A z-value of 10 degrees C was estimated from non-isothermal tests. Thus, sterilisation values (F-0) estimated from this TTI would be similar to F-0-values representative of the destruction of Clostridium botulinum spores. Industrial measurements under non-isothermal conditions were conducted in metal cans processed in an FMC reel and spiral cooker-cooler and a bar simulator, and also in plastic pouches processed in a Lagarde steam-air retort. (c) 2006 Elsevier Ltd. All rights reserved.