High Pressure Processing (HPP) is a safe and effective process for improving the microbial safety and
shelf-life of foods. Salmonella is a common contaminant in poultry meat and is frequently responsible for
foodborne illness associated with contaminated poultry meat. In this study the inactivation of a fiveisolate
cocktail of Salmonella spp. in ground chicken (95% lean) using HPP at refrigeration temperature
(4e6 C) was studied. More than 5-log CFU/g inactivation was achieved at 450 MPa for10 min. In
contrast, HPP treatment at 250 MPa or 350 MPa (single-cycle, 15 min) inactivated 0.5 log or 1.7 log CFU/g,
respectively. The multiple-cycle HPP mode at 250 or 350 MPa (3-cycle with 5 min/cycle) showed higher
cell reduction at 1.3 or 3.3 log CFU/g, respectively. HPP at 550 MPa for 10 min may reduce the cell counts,
initially at 8.5 log CFU/g, to below the detection limit (1.0 log CFU/g) in current study. The images
(electron microscopy) of the HPP shocked cells were examined for structural damage, which demonstrated
that Salmonella cells may still look intact (with damages on rough/irregular surface at 450 MPa
stress) under Scanning Electron Microscopy (SEM), but have significant damage internally (voids and
uneven mass distribution patterns) under Transmission Electron Microscopy (TEM).