Modelling inactivation of Staphylococcus aureus and Yersinia enterocolitica by high-pressure homogenisation at different temperatures.

A detailed study of the inactivation of Staphylococcus aureus and Yersinia enterocolitica by high-pressure homogenisation was performed at, respectively, 25 and 35 different combinations of process temperature and process pressure covering a range of 5-50 degrees C and 100-300 MPa. It appeared that in the entire studied pressure-temperature domain, S. aureus was more resistant to high-pressure homogenisation than Y. enterocolitica. Furthermore, the effect of the process pressure on the inactivation of S. aureus was considerably smaller than on the inactivation of Y. enterocolitica. Also, temperature between 5 and 40 degrees C did not affect inactivation of S. aureus by high-pressure homogenisation, while Y. enterocolitica inactivation was affected by temperature over a much wider range. Different mathematical models were compared to describe the inactivation of both bacteria under the experimental conditions applied. Such pressure-temperature inactivation models form the engineering basis for design, evaluation and optimisation of high-pressure homogenisation processes as a new preservation technique.