title: A quantitative microbiological exposure assessment model for Bacillus cereus in REPFEDs.
abstract: One of the pathogens of concern in refrigerated and processed foods of extended durability (REPFED) is psychrotrophic Bacillus cereus, because of its ability to survive pasteurisation and grow at low temperatures. In this study a quantitative microbiological exposure assessment (QMEA) of psychrotrophic B. cereus in REPFEDs is presented. The goal is to quantify (i) the prevalence and concentration of B. cereus during production and shelf life, (ii) the number of packages with potential emetic toxin formation and (iii) the impact of different processing steps and consumer behaviour on the exposure to B. cereus from REPFEDs. The QMEA comprises the entire production and distribution process, from raw materials over pasteurisation and up to the moment it is consumed or discarded. To model this process the modular process risk model (MPRM) was used (Nauta, 2002). The product life was divided into nine modules, each module corresponding to a basic process: (1) raw material contamination, (2) cross contamination during handling, (3) inactivation during preparation, (4) growth during intermediate storage, (5) partitioning of batches in portions, (6) mixing portions to create the product, (7) recontamination during assembly and packaging, (8) inactivation during pasteurisation and (9) growth during shelf life. Each of the modules was modelled and built using a combination of newly gathered and literature data, predictive models and expert opinions. Units (batch/portion/package) with a B. cereus concentration of 10(5)CFU/g or more were considered 'risky' units. Results show that the main drivers of variability and uncertainty are consumer behaviour, strain variability and modelling error. The prevalence of B. cereus in the final products is estimated at 48.6% (±0.01%) and the number of packs with too high B. cereus counts at the moment of consumption is estimated at 4750 packs per million (0.48%). Cold storage at retail and consumer level is vital in limiting the exposure. Four key points were identified (i) raw material contamination, (ii) recontamination during packaging, (iii) reduction during pasteurisation and cooking and (iv) cold storage at retail and consumer level.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium. Electronic address: jeff.daelman@ugent.be.
authors.forename: Jeff
authors.initials: J
authors.lastname: Daelman
authors.forename: Jeanne-Marie
authors.initials: JM
authors.lastname: Membré
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Jacxsens
authors.forename: An
authors.initials: A
authors.lastname: Vermeulen
authors.forename: Frank
authors.initials: F
authors.lastname: Devlieghere
authors.forename: Mieke
authors.initials: M
authors.lastname: Uyttendaele
mesh_terms: D001409:Bacillus cereus / Q000254:growth & development / Q000502:physiology*; D001427:Bacterial Toxins / Q000378:metabolism; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005511:Food Handling; D005516:Food Microbiology / Q000706:statistics & numerical data; D006801:Humans; D008962:Models, Theoretical; D018570:Risk Assessment / Q000379:methods*
chemical_list: D001427:Bacterial Toxins
keywords: Bacillus cereus; Exposure assessment; Probabilistic model; REPFEDs