The results of this research demonstrated that under all tested
conditions ILP treatment was equally effective (P > 0.05) in inactivation
of both L. monocytogenes and E. coli O157:H7 inoculated on
the surface of the slicing knife. The overall difference in the mean
log reduction achieved, between the two pathogens, was less than
0.1 log (N0/N) (4.57 log (N0/N) for L. monocytogenes and 4.62 log
(N0/N) for E. coli O157:H7). This is in agreement with the findings
of Gomez-Lopez et al. (2005a) who did not observe any difference
in susceptibility among different groups of microorganisms, after
studying 27 bacterial, yeast, and mould species. In contrast, several
previous studies have all reported the following trend of susceptibility
to ILP treatment in decreasing order: Gram-negative bacteria,
Gram-positive bacteria, and fungal spores (Anderson et al., 1999;
Rowan et al., 1999). The most probable reason for the discrepancies
between the reported findings is the difference in the experimental
setup and in the test conditions.