Estimating microbial survival parameters under high hydrostatic pressure

High hydrostatic pressure (HHP) processing is an emerging food preservation technology with minimal impact on the nutritional and sensory attributes of the food. Kinetic models that describe microbial inactivation under HHP are essential in establishing valid sterilization processes, while their applications rely on the predetermined survival parameters that define those models. In this study, an optimization algorithm was developed to estimate these parameters through finding the best fitting-curves to nonisobaric survival data. Published survival data on Escherichia coli ATCC 25922 was used to test the algorithm. The Weibull model was suitable for describing nonlinear E. coli survival curves and the new algorithm provided an accurate estimation of its survival parameters. The obtained survival parameters from either isobaric or nonisobaric data were substantially different, indicating that the accuracy of the parameters could be influenced by the accumulated microbial death during pressure come-up times. Although the algorithm was tested by using the Weibull model, it should be applicable to other inactivation kinetic models since a specific inactivation kinetics model does not need to be assumed.