title: Quantitative assessment of the impact of cross-contamination during the washing step of ready-to-eat leafy greens on the risk of illness caused by Salmonella.
abstract: The aim of this study was to develop a quantitative microbial risk assessment (QMRA) model to estimate the risk of illness caused by Salmonella in ready-to-eat (RTE) leafy greens, based on common practices in Brazilian processing plants. The risk assessment model considered five modules: in field, washing step, retail storage, home storage and dose-response. Fifty thousand iterations of a @Risk model built in Excel were run for each of sixty scenarios. These scenarios considered different initial pathogen concentrations, fractions of contaminated produce and chlorine concentrations. For chlorine, seven pre-set concentrations (0, 5, 10, 25, 50, 150 and 250mg/L) and three triangular distributions were considered [RiskTriang(0,5,10mg/L), RiskTriang(0,80,250mg/L) and RiskTriang(10,120,250mg/L)]. The outputs were risk of infection, estimated number of illnesses and estimated percent of illnesses arising from cross-contamination. The QMRA model indicated quantitatively that higher chlorine concentrations resulted in lower risk of illness. When simulation was done with <5mg/L of chlorine, most (>96%) of the illnesses arose from cross-contamination, but when a triangular distribution with 10, 120 and 250mg/L of chlorine was simulated, no illnesses arising from cross-contamination were predicted. Proper control of the sanitizer in the washing step is essential to reduce initial contamination and avoid cross-contamination.
authors.affiliation: Food Research Center, Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, B14, 05508-000, Sao Paulo, SP, Brazil; Department of Food Science, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 65 Dudley Road, 08901-8520 New Brunswick, NJ, USA. Electronic address: danielemaffei@usp.br.
authors.forename: Daniele F
authors.initials: DF
authors.lastname: Maffei
authors.affiliation: Department of Food Science, Faculty of Food Engineering, University of Campinas, Rua Monteiro Lobato, 80, 13083-862, Campinas, SP, Brazil. Electronic address: and@unicamp.br.
authors.forename: Anderson S
authors.initials: AS
authors.lastname: Sant'Ana
authors.affiliation: Food Research Center, Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, B14, 05508-000, Sao Paulo, SP, Brazil. Electronic address: bfranco@usp.br.
authors.forename: Bernadette D G M
authors.initials: BD
authors.lastname: Franco
authors.affiliation: Department of Food Science, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 65 Dudley Road, 08901-8520 New Brunswick, NJ, USA. Electronic address: don.schaffner@rutgers.edu.
authors.forename: Donald W
authors.initials: DW
authors.lastname: Schaffner
mesh_terms: D001938:Brazil; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D057140:Fast Foods / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling; D005516:Food Microbiology; D018515:Plant Leaves / Q000382:microbiology*; D018570:Risk Assessment; D012475:Salmonella / Q000302:isolation & purification; D014675:Vegetables / Q000382:microbiology*
chemical_list: D002713:Chlorine
keywords: Cross-contamination; Leafy greens; Risk assessment; Salmonella; Washing