Modeling the effect of inoculum size and acid adaptation on growth/no growth interface of Escherichia coli O157:H7

Skandamis, Panos; Stopforth, Jarret D.; Kendall, Patricia A.; Belk, K. E.; Scanga, J. A.; Smith, G. C.; Sofos, John N.

doi:10.1016/j.ijfoodmicro.2007.08.028

Cited by 56 publications

(40 citation statements)

References 49 publications

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“…When used in food systems, this model has a lower concordance rate than when it is applied to laboratory media experiments. Most of the growth boundary studies carried out with broth reported percent concordance rates higher than 0.97 (4,24,42,48) in contrast to the 0.7 and 0.91 values previously reported in food experiments (3,19). In both these cases, the use of the ordinary logistic regression model for food systems was considered adequate, despite the higher variability associated with dynamic food systems, as reflected in the poorer fit of the model.…”

Section: Discussionmentioning

confidence: 74%

“…McMeekin et al (33) used this approach to model the effects (additive or synergistic) of various hurdles on the probability of growth. Logistic models have been used to predict growth limits of, for example, Escherichia coli (37,42) or Shigella flexneri (38). However, most studies modeling the behavior of L. monocytogenes have been undertaken in laboratory media because their use has many advantages, including the homogeneity of substrate, the constant intrinsic factors, the use of optical density for analysis, and the limited labor required compared to experiments with foods.…”

Section: Discussionmentioning

confidence: 99%

“…The remaining cases were considered " no growth." The 0.5-logincrease criterion was taken from Bolton and Frank (3), Koutsoumanis and Sofos (25), and Skandamis et al (42).…”

Section: Determination Of a Dominant Strainmentioning

confidence: 99%

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Effect of pH and Water Activity on the Growth Limits of Listeria monocytogenes in a Cheese Matrix at Two Contamination Levels

Schvartzman

Belessi

Butler

et al. 2011

Journal of Food Protection

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Listeria monocytogenes can proliferate at the beginning of cheesemaking as the conditions favor growth. The objective of this study was to establish the growth limits of L. monocytogenes in a cheese matrix, in case of potential contamination of the milk prior to cheese manufacture. A semisoft laboratory scale model cheese system was made at different initial pH and water activity (a(w)) levels with a mix of two strains of L. monocytogenes. A factorial design of five pH values (5.6 to 6.5), four a(w) values (0.938 to 0.96), and two L. monocytogenes inoculation levels (1 to 20 CFU/ml and 500 to 1,000 CFU/ml) was carried out. Each combination was evaluated in six independent replicates. In order to determine if there was a dominant strain, isolated colonies from the cheeses were analyzed by pulsed-field gel electrophoresis. The data relating to growth initiation were fitted to a logistic regression model. The a(w) of milk influenced the probability of growth initiation of L. monocytogenes at both low and high contamination levels. The pH, at the concentrations tested, had a lower effect on the probability of growth initiation. At pH 6.5 and a(w) of 0.99 for low contamination levels and pH 6.5 and a(w) of 0.97 for high contamination levels, increases in population of up to 4 and 2 log were observed at low and high contamination levels, respectively. This shows that if conditions are favorable for growth initiation at the early stages of the cheesemaking process, contamination of milk, even with low numbers, could lead to L. monocytogenes populations that exceed the European Union's microbiological limit of 100 CFU/g of cheese.

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

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Effect of pH and Water Activity on the Growth Limits of Listeria monocytogenes in a Cheese Matrix at Two Contamination Levels

Schvartzman

Belessi

Butler

et al. 2011

Journal of Food Protection

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“…Unintentional contact of water and acidic carcass run-off fluids in meat plants, e.g. Studies by Skandamis et al (2007) demonstrated that E. coli O157:H7 cells, for example, exposed to lactic acid washing solutions were able to grow at lower pH than non-exposed cells, i.e. Pathogens residing on carcass surfaces and/or the meat processing environment, exposed (repetitively) to these sublethal acid stress conditions may become acid adapted, and thus, increase their tolerance to acid, or be selected for inherent reduced susceptibility to acid (Samelis et al, 2001(Samelis et al, , 2002Samelis and Sofos, 2003).…”

Section: Evaluation On the Information Providedmentioning

confidence: 99%

Evaluation of the safety and efficacy of the organic acids lactic and acetic acids to reduce microbiological surface contamination on pork carcasses and pork cuts

Silano¹,

Baviera²,

Bolognesi³

et al. 2018

EFS2

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Studies evaluating the safety and efficacy of lactic and acetic acids to reduce microbiological surface contamination on pork carcasses pre-chill and pork meat cuts post-chill were assessed. Lactic acid treatments consisted of 2-5% solutions at temperatures of up to 80°C applied to carcasses by spraying or up to 55°C applied on cuts by spraying or dipping. Acetic acid treatments consisted of 2-4% solutions at temperatures of up to 40°C applied on carcasses by spraying or on cuts by spraying or dipping. The maximum treatment duration was 30 s. The Panel concluded that: [1] the treatments are of no safety concern, provided that the substances comply with the European Union specifications for food additives; [2] spraying of pork carcasses pre-chill with lactic acid was efficacious compared to untreated control, but based on the available data, the Panel could not conclude whether lactic acid was more efficacious than water treatment when spraying of pork carcasses pre-chill or pork meat cuts post-chill. The Panel concluded that dipping of pork meat cuts post-chill in lactic acid was more efficacious than water treatment. However, it could not conclude on the efficacy of acetic acid treatment of pork carcasses pre-chill and/or pork meat cuts post-chill; [3] the potential selection and emergence of bacteria with reduced susceptibility to biocides and/or resistance to therapeutic antimicrobials linked to the use of the substances is unlikely as long as Good Hygienic Practices are implemented; and [4] the release of both organic acids is not of concern for the environment, assuming that wastewaters released by the slaughterhouses are treated, if necessary, to counter the potentially low pH caused by lactic or acetic acid, in compliance with local rules.

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“…In addition they do not provide useful information such as the T min and the activation energy provided by the Belehradek and Arrhenius models. 10-30 NaCl (0.5-16.5 %), sucrose (0-8%), pH (3.5-6.0), acetic acid (0-4 %) TSB Skandamis et al, 2007 10-35 NaCl (0-10%), pH (3.52-7.32) TSB Wijtzes et al, 1993 5-35 pH (4.6-7.4), a w (0.95-0.997) Belehradek George et al, 1996 1-20 pH (4.5-7.2), lactic acid (0-20.000 mg/l), acetic acid (0-10.000 mg/l) Polynomial Farber et al, 1996 4-10 pH (5.5-6.5), atmosphere (CO 2 : 10-90%) Polynomial Fernandez et al, 1997 4-20 NaCl (0.5-8.0%), pH (4.0-7.2), atmosphere (CO 2 : 0-100%) Polynomial McClure et al, 1997…”

Section: Cardinal Parameter Models (Cpm)mentioning

confidence: 99%

Scientific Opinion on Public health risks represented by certain composite products containing food of animal origin

Cerf¹,

Koutsoumanis²,

Nguyen-Thé³

et al. 2012

EFSA Journal

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This Opinion reviews the factors that affect microbial survival and growth in composite products, and in foods in general. It concludes that the main factors to be considered are: water activity, pH, temperature and duration of storage, processing, and intensity and duration of other non-thermal physical processes applied. Prevalence and concentration of the pathogens in food are important to determine the risk for consumers. The opinion presents a review of the quantitative microbiology models and databases that can be used to provide quantitative estimations of the impact of the above factors on the survival and growth of the main bacterial pathogens. In composite products, migration and diffusion of moisture and substances among the ingredients may change their physico-chemical parameters, particularly at the interfaces. Therefore, the assessment of the risk posed by composite products needs to consider the combinations of parameters most permissive to survival and growth of pathogens. Two complementary approaches are proposed for the identification and profiling of microbiological hazards in different specific composite products. The first one is based on past outbreaks and prevalence of hazards in the products and leads to the conclusion that the most frequent hazard-composite product combinations are Salmonella in cakes and bakery products. The second one consists in decision tools based on the impact on the pathogens of food composition and food processing. Categorisation of the risk for composite products requires information on their composition, processing and further handling, which can largely differ for foods belonging to the same category. Further conditions may influence the risk and should be verified, i.e. hygienic conditions during preparation of the composite products and their ingredients, shelf-life conditions, and reliability of cooking by consumers to inactivate pathogens. The decision tools developed apply to all composite products considered by the mandate, as well as to all other foods. © European Food Safety Authority, 2012 KEY WORDSComposite product, food-borne pathogens. SUMMARYFollowing a request from the European Commission, the Panel on Biological Hazards (BIOHAZ) was asked to deliver a Scientific Opinion on public health risks represented by certain composite products containing food of animal origin.Currently, imports into the EU of composite products are subject to specific rules in relation to both public health and animal health aspects. Some derogations currently apply to those rules, and there is a need for the European Commission to develop harmonised risk-based public health rules for import of those composite products for which controls are not currently prescribed. Therefore, the European Commission requested EFSA to recommend/identify physico-chemical parameters for certain composite products containing no meat and/or less than 50% of products of animal origin that could be relevant for the growth/survival of pathogenic microorganisms of public health importan...

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Modeling the effect of inoculum size and acid adaptation on growth/no growth interface of Escherichia coli O157:H7

Cited by 56 publications

References 49 publications

Effect of pH and Water Activity on the Growth Limits of Listeria monocytogenes in a Cheese Matrix at Two Contamination Levels

Effect of pH and Water Activity on the Growth Limits of Listeria monocytogenes in a Cheese Matrix at Two Contamination Levels

Evaluation of the safety and efficacy of the organic acids lactic and acetic acids to reduce microbiological surface contamination on pork carcasses and pork cuts

Scientific Opinion on Public health risks represented by certain composite products containing food of animal origin

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