Sammendrag
Effective cleaning and disinfection (C&D) is pivotal for the control of Listeria monocytogenes
in food processing environments. Bacteria in biofilms are protected from biocidal action, and effective
strategies for the prevention and removal of biofilms are needed. In this study, different C&D
biofilm control strategies on pre-formed L. monocytogenes biofilms on a conveyor belt material were
evaluated and compared to the effect of a conventional chlorinated, alkaline cleaner (agent A).
Bacterial reductions up to 1.8 log were obtained in biofilms exposed to daily C&D cycles with
normal user concentrations of alkaline, acidic, or enzymatic cleaning agents, followed by disinfection
using peracetic acid. No significant differences in bactericidal effects between the treatments were
observed. Seven-day-old biofilms were more tolerant to C&D than four-day-old biofilms. Attempts to
optimize biofilm eradication protocols for four alkaline, two acidic, and one enzymatic cleaning agent,
in accordance with the manufacturers’ recommendations, were evaluated. Increased concentrations,
the number of subsequent treatments, the exposure times, and the temperatures of the C&D agents
provided between 4.0 and >5.5 log reductions in colony forming units (CFU) for seven-day-old
L. monocytogenes biofilms. Enhanced protocols of conventional and enzymatic C&D protocols have the
potential for improved biofilm control, although further optimizations and evaluations are needed.
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