Time-temperature integrators for thermal process evaluation

Consumer demand for new and higher-quality foods has forced the food industry to develop new sterilization and pasteurization systems and to optimize current practices so that such demands can be satisfied without any negative impact on food safety. One of the main areas of current investigation is related to the use of heat in the food preservation, the main objective is the application of the minimum heat levels to destroy or to inhibit the development of the pathogen and spoiling microorganisms and to provide food with a longer shelf life. Technological developments such as treatment with high temperatures for short time periods (HTST or UHT) and the aseptic processing of food containing particles are very interesting because of the potential advantages that they offer from the point of view of nutritive and organoleptic food quality. With the objective of guaranteeing the microbiological safety of food preserved by heat, a strict evaluation of the thermal process is necessary. However, the conventional validation methods of these preservation processes are not always appropriate due to the way in which the food is produced and thermally processed. The time temperature integrators (TTIs) offer an alternative to the thermocouples and the conventional microbiological methods used to quantify the impact of thermal treatment on the microorganisms and others of food components such as vitamins or enzymes. In this chapter, a historical perspective is given on the systems used in the evaluation of the thermal processes and the development and the use of the TTI as a tool for ensuring the safety of thermally processed foods is described.