Journal of food processing and preservation vol:17 issue:5 pages:369-389
Recently, the use of Time Temperature Integrators (TTIs) as an alternative means of process evaluation, besides in situ process monitoring and the physical-mathematical method, has received a lot of attention. The stringent requirement to which an adequate functioning TTI should respond, i.e., the temperature dependence of reaction rate constants for the monitored target quality attribute and the TTI shall be identical, is hard to realize in practice. Therefore, multicomponent TTIs have been suggested to evaluate the integrated impact of time and temperature on a target quality attribute. These monitoring devices consist of a number of temperature sensitive units, each with its own response of reaction rates to temperature. The question how from the combined reading of these individual systems, the impact of the heating process on a target quality parameter can be predicted has not yet been answered. In this theoretical study, we critically consider the restrictions of two interpolation methods in determining the impact on a target quality attribute from the reading of three other temperature sensitive systems. Possibilities of the 'Equivalent Point Method' and a polynomial expression as interpolation method are tested. Success of these transformations depends on kinetic characteristics of the components in the multicomponent TTI system and the actual product temperature history. Since only limited information is available on the product temperature history in processing conditions when TTIs are used, caution must be used in applying these interpolations. A single-component TTI with an activation energy (or z-value) identical to the target quality attribute activation energy (z-value) may be preferable to estimate the impact of the thermal treatment.