Reduction of Listeria monocytogenes and Campylobacter spp. biofilm on conveyor belts using different cleaning and disinfection regimes

Removal of biofilm is essential in food production environments, such as slaughterhouses and meat processing facilities, to prevent the persistence and spread of spoilage and pathogenic microorganisms that compromise food safety. Thus, efficient cleaning and disinfection (C&D) are crucial. This study aimed to compare the efficacy of 15 commercial C&D treatments, including chemicals diluted at different concentrations of the concentrate, to reduce Listeria monocytogenes and Campylobacter spp. biofilm. Chlorinated alkaline, acidic, and enzymatic detergents alone or combined with chlorinated alkaline, acidic, electrochemically activated water (ECA), and alcohol disinfection were applied on pre-formed L. monocytogenes and Campylobacter spp. biofilms on woven conveyor belt material. The most efficient treatment was high concentration (6%) chlorinated alkaline cleaning combined with 70% alcohol (1.7 and 2.2 log reduction for L. monocytogenes and Campylobacter spp., respectively), followed by high concentration (6%) chlorinated alkaline cleaning and chlorinated alkaline disinfection (3%) (1.5 and 1.7 log reduction for L. monocytogenes and Campylobacter spp., respectively). The latter was superior to ECA combined with the same cleaning agent. For certain treatments, an increased concentration resulted in higher bacterial reduction, such as acidic C&D agents which improved reductions with 0.7-1.0 log. Biofilm removal was not enhanced when enzymatic cleaners replaced acidic or chlorinated alkaline cleaning agents. These findings indicate that, when applied at standard manufacturer concentrations, commonly used C&D agents are unable to remove biofilms of L. monocytogenes and Campylobacter spp. from conveyor belts. This emphasises the need for science-based guidelines to optimise C&D protocols in meat production facilities. • Highest biofilm removal was achieved by chlorinated alkaline agents and alcohol • Enzymatic cleaning did not improve biofilm reduction • Increasing the concentration of acidic agents improved biofilm removal • High level of bacterial biofilm remained after cleaning and disinfection