Evaluating the efficacy of peroxyacetic acid in preventing salmonella cross-contamination on tomatoes in a model flume system

Authors: PABST, CHRISTOPHER - University Of Florida; KHAREL, KARUNA - University Of Florida; DE, JAYSANKAR - University Of Florida; Bardsley, Cameron; BERTOLDI, BRUNA - University Of Florida; SCHNEIDER, KEITH - University Of Florida

Submitted to: Heliyon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2024
Publication Date: 5/17/2024
Citation: Pabst, C.R., Kharel, K., De, J., Bardsley, C.A., Bertoldi, B., Schneider, K. 2024. Evaluating the efficacy of peroxyacetic acid in preventing salmonella cross-contamination on tomatoes in a model flume system. Heliyon. 10(10). Article e31521. https://doi.org/10.1016/j.heliyon.2024.e31521.
DOI: https://doi.org/10.1016/j.heliyon.2024.e31521

Interpretive Summary: Tomatoes are often washed and moved through the packinghouse in a flume tank following harvest. This present a potential for contamination of foodborne pathogens such as Salmonella. In order to prevent cross-contamination of tomatoes from contaminated water or tomatoes, a sanitizer is often added to the flume tank water. A chlorine based sanitizer is often used but may have problems maintaining efficacy when there is a build up of dirty or other organic material in the flume tank. This study evaluated the effectiveness of peroxyacetic acid as an alternative to preventing cross-contamination of Salmonella on tomatoes. This study also investigated how peroxyacetic acid concentration, organic load, and Salmonella load influenced cross-contamination. The finding of the study suggest that peroxyacetic acid is effective at prevent cross-contamination at lower Salmonella loads but the sanitizer effectiveness was influenced by peroxyacetic acid concentration and organic load.

Technical Abstract: The use of flume tanks for tomato processing has been identified as a potential source of cross-contamination, which could result in foodborne illness. This study’s objective was to assess the efficacy of peroxyacetic acid (PAA) at a concentration of = 80 mg/L in preventing Salmonella enterica cross-contamination under various organic loads in a benchtop model tomato flume tank. The stability of 80 mg/L PAA at different chemical oxygen demand (COD) levels was also tested. Tomatoes were spot inoculated with a five-serovar rifampin-resistant (rif+) Salmonella cocktail (106 or 108 CFU/tomato). Inoculated (n=3) and uninoculated (n=9) tomatoes were introduced into the flume system containing 0-80 mg/L PAA and 0 or 300 mg/L COD. After washing for 30, 60, or 120 s, uninoculated tomatoes were sampled and analyzed for cross-contamination. All experiments were conducted in triplicate. Increasing the organic load (measured as COD) affected the stability of PAA in water with significantly faster dissociation when exposed to 300 mg/L COD. The concentration of PAA, inoculum level, COD levels, and time intervals were all significant factors that affected cross-contamination. At the high inoculum level (108 CFU/tomato), cross-contamination occurred even when 80 mg/L PAA was present in the model flume tank, regardless of the organic load level. When the tomatoes were contaminated at a level of 106 CFU/tomato, as low as 5 mg/L of PAA was effective in preventing cross-contamination at 0 mg/L COD, however, 100% tomatoes (9/9) were positive when the organic load increased to 300 mg/L COD. When PAA concentration was increased to 10 mg/L, it was effective in preventing cross-contamination in the model flume tank, regardless of the presence of organic load. These results suggest that using PAA at concentrations below the maximum limit remains effective in limiting bacterial cross-contamination and offers a more environment-friendly option for tomato packinghouse operators.