Estimating thermal degradation kinetics parameters from the endpoints of non-isothermal heat processes or storage

Where specimen retrieval for chemical analysis is not an option, as during a UHT process, or impeded by logistic considerations as in storage studies, a thermal degradation reaction's kinetic parameters can be estimated from the nutrient's or other compound's final concentrations after three or more known but different non-isothermal temperature histories. Provided the reaction follows fixed yet unknown order kinetics and its rate constant's temperature dependence follows a two-parameter algebraic model, the kinetic parameter estimation can be done by solving three simultaneous equations, themselves being the numerical solutions of three corresponding differential rate equations. In computer simulations of heat sterilization processes and storage under oscillating temperatures that include small experimental scatter, the reaction's kinetic order, its rate at a reference temperature, and the rate's temperature dependence were estimated from the final concentrations and correctly predicted dynamic degradation curves not used in their determination. The method's predictive ability was also tested with published experimental isothermal degradation data on ascorbic acid, patulin, sulforaphane, and thiamine, where the final concentrations at temperatures not used in the parameters determination were estimated from three endpoints. The described method only works where the above mentioned conditions are fully satisfied. Where applicable, it eliminates the need to experimentally determine sets of complete isothermal degradation curves, which might be impractical or too costly. (C) 2014 Elsevier Ltd. All rights reserved.