Predictive modelling of growth of Yersinia enterocolitica: the effects of temperature, pH and sodium chloride.

The growth responses of Yersinia enterocolitica as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-6.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 5-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates for generation time in media and a range of foods including meat and meat products, milk, eggs, fish and tofu. All predictions were consistently 'fail-safe'.