Theoretical Consideration on the Influence of the z-Value of a Single Component Time/Temperature Integrator on Thermal Process Impact Evaluation
- 1 January 1995
- journal article
- Published by Elsevier in Journal of Food Protection
- Vol. 58 (1) , 39-48
- https://doi.org/10.4315/0362-028x-58.1.39
Abstract
The allowed difference in z-value between a single component time/temperature integrator (SCTTI) and target attribute to measure the impact of a thermal process with a given accuracy was examined theoretically. For isothermal heating profiles, the issue and the degree of over- or underestimation of the actual process-value can be predicted as a function of z-value difference and reference temperature. The closer the processing temperature approaches reference temperature, the larger the allowed difference in z-value. As target attributes are characterized by a higher z-value, the allowed z-value difference between SCTTI and target attribute increases. For non-isothermal heating profiles, over- or underestimation depends in addition on the temperature history of the product. In order to obtain a safe estimate of the impact value, whatever the shape of the time/temperature profile, a new approach is suggested based on a SCTTI with a z-value below the target z-value in combination with the use of a reference temperature above or equal to the maximum processing temperature.Keywords
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