Parameter kinetic models, data storage

The storage of data for hundreds of runs and the calculation of alpha at the maximum rate represent conventional applications of the computer to the handling of large amounts of data and complex calculations. Programs for obtaining best fit values of parameters for several kinetic models and for simulating a-t data represent unique applications of the computer to degradation kinetics and will be described. 

To predict nutrient deterioration, knowledge of the reaction rate as a function of temperature of storage or processing is needed. The kinetics of ascorbic acid destruction have been examined most extensively in model systems, with particular attention being given to intermediate moisture foods (17, 71,78,79). Most of the data available for vitamin C losses in actual food systems are insuflBcient to calculate the kinetic parameters needed to predict losses during heat treatment or storage. 

PBPK models are particularly useful for interspecies extrapolations of dose-response data. In using a PBPK model of uptake, distribution, and elimination, an exponential power (e.g., 0.75) of the body weight is used to scale the cardiac output and ventilation rate between the laboratory species (typically rat) and humans. A PBPK model will therefore contain adequate logic to account for routes of administration, storage tissues and residence time therein, elimination rates, and sufficient mathematical detail to mimic the integration of these processes. It is important that the model parameters (e.g., elimination rates) be validated as much as possible by separate kinetic studies in the relevant species. The ultimate test of the model is how the model predictions are for parameters such as blood levels, rate of metabolism, and tissue concentrations relative to real-life animal data for the chemical. 

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