title: Toxin production and growth of pathogens subjected to temperature fluctuations simulating consumer handling of cold cuts.
abstract: It is crucial for the quality and safety of ready-to-eat (RTE) foods to maintain the cold chain from production to consumption. The effect of temperature abuse related to daily meals and elevated refrigerator temperatures on the growth and toxin production of Bacillus cereus, Bacillus weihenstephanensis and Staphylococcus aureus and the growth of Listeria monocytogenes and Yersinia enterocolitica was studied. A case study with temperature loggings in the domestic environment during Easter and Christmas holidays was performed to select relevant time and temperature courses. A model for bacterial surface growth on food using nutrient agar plates exposed to variations in temperatures was used to simulate food stored at different temperatures and exposed to room temperature for short periods of time. The results were compared with predicted growth using the modeling tool ComBase Predictor. The consumers exposed their cold cuts to room temperatures as high as 26.5°C with an average duration of meals was 47 min daily for breakfast/brunch during the vacations. Short (≤ 2 h) daily intervals at 25°C nearly halved the time the different pathogens needed to reach levels corresponding to the levels associated with human infection or intoxication, compared with the controls continuously stored at refrigerator temperature. Although the temperature fluctuations affected growth of both B. weihenstephanensis and S. aureus, toxin production was only detected at much higher cell concentrations than what has been associated with human intoxications. Therefore, growth of L. monocytogenes and Y. enterocolitica was found to be the limiting factor for safety. In combination with data on temperature abuse in the domestic environment, modeling programs such as ComBase Predictor can be efficient tools to predict growth of some pathogens but will not predict toxin production.
authors.affiliation: Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway. Electronic address: elin.rossvoll@nofima.no.
authors.forename: Elin
authors.initials: E
authors.lastname: Røssvoll
authors.affiliation: Norwegian University of Life Sciences, School of Veterinary Science, P.O. Box 5003, NO-1432 Ås, Norway.
authors.forename: Helene Thorsen
authors.initials: HT
authors.lastname: Rønning
authors.affiliation: Norwegian University of Life Sciences, School of Veterinary Science, P.O. Box 5003, NO-1432 Ås, Norway.
authors.forename: Per Einar
authors.initials: PE
authors.lastname: Granum
authors.affiliation: Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Møretrø
authors.affiliation: Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway.
authors.forename: Marianne Røine
authors.initials: MR
authors.lastname: Hjerpekjøn
authors.affiliation: Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, P.O. Box 210, N-1431 Ås, Norway.
authors.forename: Solveig
authors.initials: S
authors.lastname: Langsrud
mesh_terms: D001407:Bacillus / Q000254:growth & development; D001409:Bacillus cereus / Q000254:growth & development; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D001427:Bacterial Toxins / Q000032:analysis / Q000378:metabolism*; D003257:Consumer Product Safety; D005511:Food Handling; D005516:Food Microbiology; D006801:Humans; D008089:Listeria monocytogenes / Q000254:growth & development; D008460:Meat / Q000032:analysis* / Q000382:microbiology*; D008954:Models, Biological; D012984:Software / Q000592:standards; D013211:Staphylococcus aureus / Q000254:growth & development; D013696:Temperature; D013997:Time Factors; D015008:Yersinia enterocolitica / Q000254:growth & development
chemical_list: D001427:Bacterial Toxins
keywords: Consumers; Domestic food handling; RTE food; Refrigerator; Temperature exposure