Salmonella transfer and adhesion to food contact surfaces under low-moisture conditions: influence of environmental factors and impact of dry sanitization methods.

Salmonella contamination in low-moisture foods (LMF) remains a critical concern due to its ability to persist on surfaces and resistance to sanitization. This study investigated Salmonella transfer and adhesion on polypropylene (PP) and stainless steel (SS), using soil and crushed peanut shells (CPS) as dry carriers. Additionally, the efficacy of four dry sanitization methods was assessed: UV-C light, hot air (90 °C), 70 % ethanol, and a commercial solution (25 % isopropyl alcohol and 0.015 % quaternary ammonium compound). Salmonella transfer and adhesion under low-moisture conditions was influenced (p < 0.05) by carrier type and water activity (aw), surface material, and contact time. Soil provided more favorable conditions for bacterial transfer than CPS. In addition, Salmonella transfer and adhesion was more pronounced and persistent on PP, with values exceeding those observed on SS by ca. 1 log CFU/cm2. This suggests that PP may require more frequent or intensified hygienic interventions in LMF environments. In addition, the reduction in aw favored the transfer of salmonella via soil, while the opposite was noted for CPS. In general, sanitization performance was surface-dependent. 70 % ethanol was the most effective on SS; whereas UV-C was the best option for PP, with reductions below the limit of detection after 2 min. In contrast, the commercial solution and hot air showed limited efficacy, particularly on PP, with the presence of VBNC cells. Overall, these findings can contribute to establishing decontamination strategies and understanding microbial colonization dynamics under low-moisture conditions.