Impact of Wiping Materials on the Elimination from Surfaces of Dry Surface Biofilm of Bacteria of Food Safety Concern

Salmonella spp. and Listeria monocytogenes are common foodborne pathogens that easily contaminate food preparation surfaces. Salmonella's ability to form dry surface biofilms (DSBs) likely exacerbates surface persistence, making effective removal from food contact surfaces essential. This study is the first to evaluate the efficacy of food contact surface sanitizers against artificial L. monocytogenes DSBs, with comparisons to hydrated biofilms and dried planktonic cells. We hypothesized that the effectiveness of no-rinse, quaternary ammonium compound (QAC)-based sanitizers depends on both the wiping material used and the bacterial strain present. Two preformulated no-rinse QAC sanitizers and one QAC spray were tested with six commercial wiping materials against three dried planktonic Salmonella spp. and one L. monocytogenes, as well as their DSBs, on stainless steel surfaces. Dried planktonic cells were more easily eliminated than DSBs, achieving approximately 4 log₁₀ versus 2 log₁₀ reductions, respectively. Although no-rinse QAC sanitizers are designed to reduce bacterial levels to acceptable limits, formulation constraints may limit their cleaning efficacy, particularly against DSBs in the presence of organic matter. Preformulated QAC wipes were less effective than spraying the sanitizer followed by wiping. Wiping material type significantly influenced efficacy: paper towels significantly outperformed cloths, though performance varied among brands, and one sponge was the most effective overall. This study underscores the need to carefully select wiping materials and no-rinse food contact surface sanitizers to eliminate Salmonella and Listeria DSBs, ensuring effective sanitation practices in foodservice settings.