Microbiological changes in pressurized, prepackaged sliced cooked ham.

This was a study of the influence of high-pressure conditions (200 and 400 MPa, 5 and 20 min, 7 degrees C) on microbiological quality and water-binding properties of vacuum-prepackaged sliced cooked ham and how this affects microbiological changes during chilled storage (2 degrees C). Pressurization caused a degree of microbiological inactivation, which increased with pressure level and processing time. Pressurization at 400 MPa significantly reduced the total viable count and lactic acid bacteria to the extent that after 20 min no Enterobacteriaceae, Baird Parker flora, or Brochothrix thermosphacta were detected throughout any of the chilled storage periods studied. In general, gram-positive flora was more resistant to pressure than gram-negative flora. The fact that high pressure (400 MPa) causes considerable inactivation of microorganisms could be used to prolong the shelf life of vacuum-prepackaged sliced cooked ham.