Attachment of Salmonella Typhimurium and survival on post-harvest produce and seed

Authors: Olanya, Modesto; Mukhopadhyay, Sudarsan; Ukuku, Dike; Niemira, Brendan; Uknalis, Joseph

Submitted to: Food Science and Technology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2024
Publication Date: 4/5/2024
Citation: Olanya, O.M., Mukhopadhyay, S., Ukuku, D.O., Niemira, B.A., Uknalis, J. 2024. Attachment of Salmonella Typhimurium and survival on post-harvest produce and seed. Food Science and Technology Research. 2024(3):457-465. https://doi.org/10.3136/fstr.FSTR-D-24-00032.
DOI: https://doi.org/10.3136/fstr.FSTR-D-24-00032

Interpretive Summary: Food safety is of considerable interest to consumers, the food industry and government agencies, as safe and nutritious food is essential for a healthy society. In this study, we evaluated the effects of storage temperatures, the presence of a chemical compound (LAPY), produce decontamination with water rinse, and a bacterial competitor (Bacillus Natto, non-pathogen) that could be used to impede Salmonella attachment and pathogen survival on produce. We found that storage temperature influences the strength of Salmonella attachment, which was greater on pistachio and soybean than on alfalfa and carrot produce. While the application of the chemical compound LAPY led to high Salmonella reduction (low attachment) on produce types, the bacterial competitor had limited effect. Physical decontamination with peptone water rinse reduced bacteria attachment and limited its survival. Selective application of decontamination measures on post-harvest produce can limit Salmonella attachment, its survival and enhance produce safety.

Technical Abstract: Salmonella contamination of post-harvest produce has been a persistent problem worldwide. We determined the effects of storage temperature (5 and 25°C), lauric acid amide pyrrolidine (LAPY), a bacterial competitor (Bacillus subtilis) and physical decontamination on the attachment and survival of Salmonella on post-harvest produce. Microbial populations on untreated post-harvest produce varied with produce types as aerobic mesophilic bacteria (AMB) were greater than 7.0 logs on alfalfa sprouts, but lactic acid bacteria (LAB) were below detection (< 1 log). On pistachio and soybean, populations of Pseudomonas sp., AMB, yeast and molds, and LAB were also below detection level (<1 log CFU/g). Storage temperature influenced the strength (SR-values) of Salmonella attachment (SR-values) for varying produce types. SR-values were greater on pistachio and soybean (0.53-0.76) than on alfalfa and carrot (0.10-0.13). The application of LAPY on pathogen-inoculated produce resulted in significantly greater pathogen reduction on alfalfa, pistachio and soybean (2.1-3.0 logs), but not on carrot (<1.5 log). The application of B. subtilis, a bacterial competitor in combination with Salmonella Typhimurium did not result in any significant reductions in pathogen populations. Physical decontamination of pathogen-inoculated produce by water rinse significantly (P<0.05) reduced Salmonella attachment and bacterial populations on produce. These results indicate that mitigation of Salmonella attachment by selective application of post-harvest intervention and decontamination measures may limit attachment, pathogen survival and lead to enhanced post-harvest produce safety.