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Chapter 4
4.5. Summary
The research presented in this chapter indicates that there are a number of
inconsistencies in the previously published literature in this area. The
method chosen for biofilm formation may have a relationship with the
amount of biofilm formed on a surface and the resistance of the biofilm to
disinfectant treatment. Although standards are emerging the standards
have significant limitations such as the time allocated for biofilm
development and it is not clear how widely adopted they will be. Moreover,
there is evidence presented in this chapter to suggest that the current CEN
standards for examining the efficacy of disinfectant products in broth
dilutions such as EN1040 may be of limited value, if the bacteria have
formed a biofilm on the surfaces.
Secondly, most other research did not achieve a 4 log 10 reduction in the
number of cells recovered from an established biofilm this was also found
in most instances in this work -with the exception of sodium hydroxide
against a 48 hour biofilm. However the log 10 reduction after contact with
the disinfectants presented in this work was in most cases lower than what
has been reported elsewhere. This variation may be a reflection on the
differences between methods, disinfectants and strains. This is a
considerable uncertainty as to which model best reflects actual conditions
in the food processing environment although there is a view that the CBR
may provide a more robust method for assessing the ability of Salmonella
to survive disinfectant treatment compared with other methods.
Furthermore, laboratory studies of disinfectants used for control of
Salmonella biofilm which focus on standard-48 hour biofilm may have
limited applicability in food processing environments. As a result, the focus
of the disinfectant studies against an established biofilm changed to 168
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