Reliability of time temperature indicators under temperature abuse

The present study systematically examined the reliability of 7 MonitorMark time temperature indicators (TTI's) in isothermal and non-isothermal scenarios simulating temperature abuse. The 'reaction order' (m) of the response function varies from 0.16 to - 3.94. The response of the TTI's under isothermal storage agreed with both the Arrhenius and shelf life plot models, and the calculated activation energies range from 23.3 to 31.3 kcal/mol. Using m and k values from the isothermal experiments, all the TTI's reported the shelf life under temperature-abuse storage within a safe margin. Five indicators showed a positive "history effect". Given the positive history effect in the studied TTI's and their activation energy range, it is suggested that they may be useful when microbial growth is the major deteriorative mode of the food.