The effect of single-cycle and multiple-cycle high hydrostatic pressure (HHP) treatments on the survival of three
Salmonella
Enteritidis strains in chicken breast fillets was investigated. The surface of fillets was inoculated with a
cocktail of three
Salmonella
strains at approximately 10
7
colony-forming units (CFU)
=
g, and held at 4
8
C for 20 hours
before HHP treatments. Reduction of
Salmonella
counts on tryptic soy agar (TSA) by single-cycle treatments
at 300 MPa and 12
8
C ranged from 0.58 log CFU
=
g for a 0-minute (no dwell time) cycle to 3.35 log CFU
=
gfora
20-minute cycle, whereas with 400 MPa treatments the decline ranged from 0.93 log CFU
=
g to more than 5 log
CFU
=
g, respectively. The 4.8 log unit reduction in
Salmonella
counts on TSA achieved by a 15-minute treatment at
400 MPa should suffice to eliminate the pathogen naturally present in contaminated chicken meat. When plated on
Salmonella Shigella agar (SSA), the reduction of
Salmonella
counts by single-cycle treatments at 300 MPa and 12
8
C
ranged from 0.69 log CFU
=
g for a 0-minute cycle to 4.21 log CFU
=
g for a 20-minute cycle, and with 400 MPa
treatments from 1.25 log CFU
=
g to more than 5 log CFU
=
g, respectively. From the comparison of
Salmonella
counts
on SSA and TSA it was concluded that not only the lethality but also the proportion of injured
Salmonella
cells
increased with the length of HHP treatments. The use of multiple-cycle treatments instead of single-cycle treat-
ments of the same HHP time for the inactivation of
Salmonella
Enteritidis inoculated on chicken breast fillets
showed to be more advantageous at 400 MPa than at 300 MPa. No recovery of injured
Salmonella
cells was
observed when fillets treated at 300 or 400 MPa for 5 minutes were held for 72 hours at 4
8
C