High pressure (HP) destruction kinetics of Escherichia coli (O157:H7) and Listeria monocytogenes (Scott A) in mackerel (Scomber scombrus) were evaluated. Filleted fish were made into a slurry with peptone water and inoculated with the respective microbial strain to prepare a stock culture containing 10(6)-10(7) CFU/ml. Samples were prepared for pressure treatment by heat-scaling 10 ml portions of stock culture in sterile plastic bags. Pressure treatments (250 and 400 MPa for 0-60 min) were given at room temperature (20-25 degrees C) in an isostatic press. Survival curves were established based on residual counts following treatment. Destruction kinetics were described as a dual effect, an initial destruction resulting from a pressure pulse (pulse effect) followed by a first order rate of destruction during the pressure holding time. E coli was found to be more sensitive to pulse pressure than L. monocytogenes. Significant differences (p < 0.05) in high pressure resistance (D-value) were found between the two microorganisms. D-values of E coli were higher than for L. monocytogenes at pressure levels >= 350 MPa, while a reverse trend was observed at lower pressures. The associated z(p) values indicated that the destruction rate of L. monocytogenes (z(p) = 103 MPa) was more sensitive to changes in pressure than E coli (z(p) = 185 MPa). Challenge studies with the more resistant pathogen, E Coli (10(7)/ml), showed that a 10D treatment followed by refrigerated storage (4-12 degrees C) prevented its recovery/growth. (C) 2008 Elsevier Ltd. All rights reserved.