High Pressure Inactivation of Enterococcus faecium–modelling and verification

Landfeld A., Strohalm J., Kýhos K., Průchova J., Houska M., Novotna P., Schlemmerova L., Smuhařova H., Spelina V., Cermak P., Pavlisova K., Měřicka P. (2009): High pressure inactivation of Enterococcus faecium – modelling and verification. Czech J. Food Sci., 27: 134–141. High-pressure inactivation data were obtained for model working suspensions of Enterococcus faecium in saline solu tions in pH range from 5.5 to 6.8, at water activity 0.99 (corresponding to the saline solution). The data were predicted for the pressure range of 450 MPa to 550 MPa, at the initial model suspension temperature 6–7°C prior to pressurising. The results indicate that E. faecium is a highly resistant organism under physiological pH values. With decreasing the substrate pH, the tolerance to the inactivation effects of high pressure decreased. The high-pressure inactiva tion proved ineffective for the above organism in the range of physiological pH values. The values for high-pressure inactivation model were specified and the calculated parameters of high-pressure inactivation were compared to the experimental data for the working suspensions of E. faecium in cow and human milks. As to cow milk, the predicted data showed some deviation from the model experimental results, while with human milk the model failed completely. High-pressure inactivation of E. faecium in human milk proved to be significantly more effective than that predicted by a model based on the saline solution.