A dynamic mathematical model of the thermal inactivation of Enterococcus faecium during bologna sausage cooking

This paper presents an example of predictive microbiology with respect to bologna sausage cooking, including both kinetic models of microbial activities and models of physical phenomena affecting the medium conditions. The ability to predict thermal inactivation of the traditional first order kinetics model was compared with the Whiting and Buchanan model, which takes both lag phase and tailing phenomena into account. These two models were transformed into dynamic models and linked to a mathematical model of heat and mass transfer during bologna sausage cooking. The combined model, solved by numerical solution in Fortran programming language, was validated by carrying out cooking tests on bologna sausages inoculated with a test microorganism, Enterococcus faccium. The model is able to simulate thermal inactivation kinetics of microorganisms if death rates are modelled according to the Whiting and Buchanan equation. Conversely, the first order kinetic equation is unreliable and risky, since it may suggest a higher death rate than that achieved. ©1997 Academic Press Limited.