Validation of Thermal Processing Using Time-Temperature Indicators as Process Probes

Peter Fryer, Mark Simmons, Karin Mehauden, Serafim Bakalis

Research output: Contribution to journalArticlepeer-review


Thermal processing is a very common technique in the food industry. Commonly foods are overprocessed to ensure safety, but this may give excessive loss of quality attributes. Thermocouples are commonly used to obtain temperature-time profiles, but for many products it is not feasible to use them. Time-temperature indicators (TTIs) are small particles containing a reactive species that can be passed through a process and then assayed to measure the process effects. A series of tests have been carried out to determine the feasibility of using TTIs to validate thermal processes, using a pilot scale process vessel. TTI results could show the effects of local wall heating and distinguish between different heating regimes. Particle paths can be quantified using Positron-Emission Particle Tracking (PEPT); for viscous fluids of the kind found in food applications there is very close match between the flow of the fluid and of the TTI. Suggestions for the use of TTIs are made.

Original languageEnglish
Pages (from-to)33-42
Number of pages10
JournalJapan Journal of Food Engineering
Issue number1
Publication statusPublished - 1 Jan 2008


  • batch vessels
  • thermal modelling
  • Thermal processing
  • time-temperature integrators

ASJC Scopus subject areas

  • Food Science
  • Industrial and Manufacturing Engineering


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