title: A Theoretical Analysis for Assessing the Variability of Secondary Model Thermal Inactivation Kinetic Parameters.
abstract: Traditionally, for the determination of the kinetic parameters of thermal inactivation of a heat labile substance, an appropriate index is selected and its change is measured over time at a series of constant temperatures. The rate of this change is described through an appropriate primary model and a secondary model is applied to assess the impact of temperature. By this approach, the confidence intervals of the estimates of the rate constants are not taken into account. Consequently, the calculated variability of the secondary model parameters can be significantly lower than the actual variability. The aim of this study was to demonstrate the influence of the variability of the primary model parameters in establishing the confidence intervals of the secondary model parameters. Using a Monte Carlo technique and assuming normally distributedDTvalues (parameter associated with a primary inactivation model), the error propagating on theDTrefandz-values (secondary model parameters) was assessed. WhenDTconfidence intervals were broad, the secondary model's parameter variability was appreciably high and could not be adequately estimated through the traditional deterministic approach that does not take into account the variation on theDTvalues. In such cases, the proposed methodology was essential for realistic estimations.
authors.affiliation: Department of Food Technology, Technological Educational Institute of Athens, Athens 12210, Greece. mgian@teiath.gr.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Giannakourou
authors.affiliation: Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens 11855, Greece. stoforos@aua.gr.
authors.forename: Nikolaos G
authors.initials: NG
authors.lastname: Stoforos
keywords: DT and z-values; Monte Carlo; confidence intervals; error propagation; kinetics