title: Modeling transfer of Escherichia coli O157:H7 and Listeria monocytogenes during preparation of fresh-cut salads: impact of cutting and shredding practices.
abstract: Cutting and shredding of leafy vegetables increases the risk of cross contamination in household settings. The distribution of Escherichia coli O157:H7 and Listeria monocytogenes transfer rates (Tr) between cutting knives and lettuce leaves was investigated and a semi-mechanistic model describing the bacterial transfer during consecutive cuts of leafy vegetables was developed. For both pathogens the distribution of log10Trs from lettuce to knife was towards low values. Conversely log10Trs from knife to lettuce ranged from -2.1 to -0.1 for E. coli O157:H7 and -2.0 to 0 for L. monocytogenes, and indicated a more variable phenomenon. Regarding consecutive cuts, a rapid initial transfer was followed by an asymptotic tail at low populations moving to lettuce or residing on knife. E. coli O157:H7 was transferred at slower rates than L. monocytogenes. These trends were sufficiently described by the transfer-model, with RMSE values of 0.426-0.613 and 0.531-0.908 for L. monocytogenes and E. coli O157:H7, respectively. The model showed good performance in validation trials but underestimated bacterial transfer during extrapolation experiments. The results of the study can provide information regarding cross contamination events in a common household. The constructed model could be a useful tool for the risk-assessment during preparation of leafy-green salads.
authors.affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Evangelia A
authors.initials: EA
authors.lastname: Zilelidou
authors.affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Virginia
authors.initials: V
authors.lastname: Tsourou
authors.affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Poimenidou
authors.affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Anneza
authors.initials: A
authors.lastname: Loukou
authors.affiliation: Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece. Electronic address: pskan@aua.gr.
authors.forename: Panagiotis N
authors.initials: PN
authors.lastname: Skandamis
mesh_terms: D019453:Escherichia coli O157 / Q000737:chemistry / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling / Q000295:instrumentation* / Q000379:methods; D018545:Lactuca / Q000382:microbiology*; D008089:Listeria monocytogenes / Q000737:chemistry / Q000254:growth & development*; D008962:Models, Theoretical; D014675:Vegetables / Q000382:microbiology*
keywords: Bacterial transfer; Cross contamination; Knives; Leafy vegetables; Modeling