Application of a log-logistic model to describe the survival of Yersinia enterocolitica at sub-optimal pH and temperature.

A log-logistic model previously used to describe the thermal inactivation of microorganisms has been applied to predict accurately the survival of Yersinia enterocolitica under conditions of sub-optimal temperatures (0-23 degrees C) and growth inhibitory pH values for a number of different acidulants. Predictions from the model were also compared to observed survival times of Y. enterocolitica in mayonnaise and were found to be in excellent agreement. However in yoghurt the model overestimated survival of this organism at both 20 and 4 degrees C but would 'fail safe' if used for predictive purposes. The discrepancy in yoghurt is discussed.