Impact of disinfectant-neutralizing buffers used for sampling methods on the viability of adherent Listeria monocytogenes cells on surfaces.

Abstract

This study assessed the impact of six disinfectant-neutralizing buffers on Listeria monocytogenes adhering to stainless steel surfaces treated with quaternary ammonium or hydrogen peroxide-based disinfectants. The goal was to evaluate potential stressors induced by these buffers during sampling, minimizing false negatives in food industry surface monitoring. Neutralizing buffers are essential in preserving bacterial viability during sample transport by counteracting residual disinfectants. L. monocytogenes populations were quantified immediately after sampling and after 24-hour incubation at 8°C, simulating transport conditions. While neutralizing buffers had minimal impact on untreated adherent cells, they significantly reduced mortality in disinfectant-treated cells. However, most buffers failed to preserve viable culturable (VC) populations after disinfection, instead promoting viable but non-culturable (VBNC) states. Notably, prolonged incubation in the Sponge neutralizer facilitated VC population recovery, likely through VBNC resuscitation or VC growth. In contrast, other buffers inhibited recovery, suggesting detrimental effects on stressed cells due to their chemical composition. These findings underscore the importance of selecting appropriate neutralizing buffers in L. monocytogenes detection, influencing food safety surveillance and risk assessment protocols.