title: Quantitative assessment of the risk of microbial spoilage in foods. Prediction of non-stability at 55 °C caused by Geobacillus stearothermophilus in canned green beans.
abstract: Microbial spoilage of canned foods by thermophilic and highly heat-resistant spore-forming bacteria, such as Geobacillus stearothermophilus, is a persistent problem in the food industry. An incubation test at 55 °C for 7 days, then validation of biological stability, is used as an indicator of compliance with good manufacturing practices. We propose a microbial risk assessment model predicting the percentage of non-stability due to G. stearothermophilus in canned green beans manufactured by a French company. The model accounts for initial microbial contaminations of fresh unprocessed green beans with G. stearothermophilus, cross-contaminations in the processing chain, inactivation processes and probability of survival and growth. The sterilization process is modeled by an equivalent heating time depending on sterilization value F₀ and on G. stearothermophilus resistance parameter z(T). Following the recommendations of international organizations, second order Monte-Carlo simulations are used, separately propagating uncertainty and variability on parameters. As a result of the model, the mean predicted non-stability rate is of 0.5%, with a 95% uncertainty interval of [0.1%; 1.2%], which is highly similar to data communicated by the French industry. A sensitivity analysis based on Sobol indices and some scenario tests underline the importance of cross-contamination at the blanching step, in addition to inactivation due to the sterilization process.
authors: INRA, UR 1204, Met@risk, Food Risk Analysis Methodologies, F-75005 Paris, France.
authors: Clémence
authors: C
authors: Rigaux
authors: CTCPA, Site Agroparc, ZA de l'aéroport, F-84911 Avignon, France.
authors: Stéphane
authors: S
authors: André
authors: INRA, UR 1204, Met@risk, Food Risk Analysis Methodologies, F-75005 Paris, France.
authors: Isabelle
authors: I
authors: Albert
authors: INRA, UMR 408, Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France; Université d'Avignon et des Pays de Vaucluse, UMR 408, Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France.
authors: Frédéric
authors: F
authors: Carlin
mesh_terms: D007887:Fabaceae / Q000382:microbiology*; D005516:Food Microbiology; D057141:Food, Preserved / Q000382:microbiology* / Q000592:standards*; D005525:Food-Processing Industry / Q000592:standards; D001411:Geobacillus stearothermophilus / Q000502:physiology*; D006358:Hot Temperature; D018570:Risk Assessment; D013171:Spores, Bacterial / Q000502:physiology; D013242:Sterilization / Q000592:standards; D014675:Vegetables / Q000382:microbiology*
keywords: Cross contaminations; Geobacillus stearothermophilus; Prevalence; Process risk model; Second order Monte Carlo simulation; Sensitivity analysis