The Gauss-Eyring model: A new thermodynamic model for biochemical and microbial inactivation kinetics

- A new kinetic model for inactivation of complex proteins is proposed.
- The primary, stochastic model is defined by a Gaussian line shape.
- There is a one-to-one correspondence with inactivation known in food microbiology.
- Model performance was tested for heat and pH treatment of protease and Listeria.
- Sub-populations and different reaction pathways lead to heterogenic responses.

A new primary model has been developed, using Gaussian distributed populations and Eyrings rate constant for the transition state, to describe inactivation kinetics of enzymes and micro-organisms subjected to heat and chemical treatment. The inactivation of both enzymes and micro-organisms could be associated with the irreversible transition to an inactivated state, as suggested by the Lumry-Eyring model for protein denaturation and enzyme inactivation. The characteristic inactivation model parameters, standard activation enthalpy and entropy, are directly related to the reference temperature and Z-value commonly used for kinetic analysis in food microbiology. An essential feature of the kinetic model is that its parameters, and hence the transition temperature, are treated as stochastic variables. The characteristic line shape of the primary model is the log-normal distribution. The performance of the model was validated, using literature data for enzyme and microbial inactivation over a wide range of temperature and pH.