High pressure inactivation of a virulent Enterococcus faecalis on dry-cured ham: Modeling the effect of processing parameters

The effect of high pressure processing parameters on the inactivation of a potentially virulent Enterococcus faecalis strain inoculated on sliced dry-cured ham was investigated. The response surface methodology was applied in combination with a central composite design of the technological parameters: including pressure (347–852 MPa), length of the treatment (2.3–15.8 min) and temperature (7.6–24.4 °C). Bacterial inactivation, as logarithmic reductions of Enterococcus spp. counts, was modeled through the backward stepwise procedure. According to the best fitting and most significant polynomial equation, pressure and time were the factors determining the Enterococcus inactivation, while temperature was not statistically significant. E. faecalis showed a notable resistance to high pressure processing, similar to that reported for Staphylococcus aureus and higher than the baroresistance of pathogens such as Listeria monocytogenes or Salmonella. To achieve 4 log reduction of E. faecalis on dry-cured ham, pressures from 750 MPa for at least 9.5 min would be required.Industrial RelevanceThe results of this work can help food processors to set optimum technological parameters of high pressure processing to inactivate undesired microorganisms in food.

► The effect of technological parameters pressure, time and fluid temperature was mathematically modeled. ► Pressure and holding time were the significant factors included in the polynomial equation. ► E. faecalis on dry-cured ham showed a high baroresistance. ► 4 log reduction requires pressures of 750 MPa (for 9.5 min) or higher. ► The model can be a useful tool for the optimization of HPP in the food industry.