Application of a frequency distribution model to describe the thermal inactivation of two strains of Bacillus cereus

Fernández, A.; Salmerón, C.; Fernández, Pablo S.; Martínez, Antonio

doi:10.1016/s0924-2244(99)00037-0

Cited by 107 publications

(70 citation statements)

References 12 publications

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“…The cumulative form of Weibull frequency distribution model was used to describe Campylobacter survival kinetics in water as it is suitable for quantifying Page 5 / 19 bacterial survival for both log and non-log linear survival curves. The Weibull model has largely been used to describe bacterial inactivation by thermal and nonthermal processes as stress resistance of a microbial population often follows a Weibull distribution (Cunhan et al, 1998;Peleg and Cole, 1998;Fernandez et al, 1999;van Boekel, 2002;Corradini and Peleg, 2003;Virto et al, 2005;Hajmeer et al, 2006). We used a logarithm decimal form of Weibull defined as follows (Mafart et al, 2002;van Boekel, 2002):…”

Section: Campylobacter Infectionsmentioning

confidence: 99%

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Guillou

Leguérinel²,

Garrec³

et al. 2008

Water Research

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The aim of the study was to examine the hypothesis emitted by Evans et al. (2003) that mineral bottled water accidentally contaminated by Campylobacter jejuni would represent a risk factor for Campylobacter infection.Culturability of C. jejuni cells inoculated in low and high mineral bottled water during storage at 4°C in the dark was performed by surface plating and modelled using the Weibull model.The loss of C. jejuni culturability observed in all conditions tested was shown to be dependent from strain, preculture condition and water composition.Following inoculation of C. jejuni, the rapid loss of culturability was not correlated to complete cell death as the passage into embryonated eggs enabled recovery of cells from the Viable But Non Culturable state.In conclusion, the sanitary risk associated to contaminated bottled water can not be excluded although it is presumably low. Culture conditions, strain and water type must be taken into account in the evaluation of the risk factor as they influence significantly Campylobacter survival in water.

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Section: Campylobacter Infectionsmentioning

confidence: 99%

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Guillou

Leguérinel²,

Garrec³

et al. 2008

Water Research

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“…An aliquot was then spread on duplicate plates of modified Fortified Nutrient Agar (FNA) (Fernández et al, 1999), and incubated at 30 °C for 3-7 days. Sporulation was checked daily by microscopic examination, and spores were harvested when at least 90% of the cells had produced spores.…”

Section: Heat Resistance Of B Cereus Sporesmentioning

confidence: 99%

Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group

Carlin

Fricker

Pielaat

et al. 2006

International Journal of Food Microbiology

140

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One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains were classified into three groups: emetic toxin (cereulide)-producing strains (n = 17), strains connected to diarrheal foodborne outbreaks (n = 40) and food-environment strains (n = 43), these latter not producing the emetic toxin. Our study revealed a shift in growth limits towards higher temperatures for the emetic strains, regardless of their origin. None of the emetic toxin-producing strains were able to grow below 10 °C. In contrast, 11% (9 food-environment strains) out of the 83 non-emetic toxin-producing strains were able to grow at 4 °C and 49% at 7 °C (28 diarrheal and 13 food-environment strains). non-emetic toxin-producing strains. All emetic toxin-producing strains were able to grow at 48 °C, but only 39% (16 diarrheal and 16 food-environment strains) of the non-emetic toxinproducing strains grew at this temperature. Spores from the emetic toxin-producing strains showed, on average, a higher heat resistance at 90 °C and a lower germination, particularly at 7 °C, than spores from the other strains. No difference between the three groups in their growth kinetics at 24 °C, 37 °C, and pH 5.0, 7.0, and 8.0 was observed. Our survey shows that emetic toxin-producing strains of B. cereus have distinct characteristics, which could have important implication for the risk assessment of the emetic type of B. cereus caused food poisoning. For instance, emetic strains still represent a special risk in heat-processed foods or preheated foods that are kept warm (in restaurants and cafeterias), but should not pose a risk in refrigerated foods.

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“…Although van Boekel's analysis focused on microbial cells, there is clear evidence that the survival curves of several bacterial spores of food safety concern can also be described by the same model. 4,5,7 The heat inactivation of bacterial cells and spores is obviously a more complex process than the degradation of a single chemical compound or the denaturation of a single enzyme. Nevertheless, both processes are manifested in similar 'survival curves', ie a plot of the fraction of surviving cells or spores versus time in the first case and the fraction of intact or active molecules versus time in the second.…”

Section: Introductionmentioning

confidence: 99%

A model of non‐isothermal degradation of nutrients, pigments and enzymes

Corradini

Peleg

2004

J Sci Food Agric

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Published isothermal degradation curves for chlorophyll A and thiamine in the range 100-150 • C and the inactivation curves of polyphenol oxidase (PPO) in the range 50-80 • C could be described by the model C(t)/C 0 = exp[−b(T )t n ] where C(t) and C 0 are the momentary and initial concentrations, respectively, b(T ) a temperature dependent 'rate parameter' and n, a constant. This suggested that the temporal degradation/inactivation events of all three had a Weibull distribution with a practically constant shape factor. The temperature dependence of the 'rate parameter' could be described by the logwhere T c is a marker of the temperature level where the degradation/inactivation occurs at a significant rate and k the steepness of the b(T ) increase once this temperature range has been exceeded. These two models were combined to produce a non-isothermal degradation/inactivation model, similar to one recently developed for microbial inactivation. It is based on the assumption that the local slope of the non-isothermal decay curve, ie the momentary decay rate, is the slope of the isothermal curve at the momentary temperature at a time that corresponds to the momentary concentration of the still intact or active molecules. This model, in the form of a differential equation, was solved numerically to produce degradation/inactivation curves under temperature profiles that included heating and cooling and oscillating temperatures. Such simulations can be used to assess the impact of planned commercial heat processes on the stability of compounds of nutritional and quality concerns and the efficacy of methods to inactivate enzymes. Simulated decay curves on which a random noise was superimposed were used to demonstrate that the degradation/inactivation parameters, k and T c , can be calculated directly from non-isothermal decay curves, provided that the validity of the Weibullian and log logistic models and the constancy of the shape factor n could be assumed.

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Application of a frequency distribution model to describe the thermal inactivation of two strains of Bacillus cereus

Cited by 107 publications

References 12 publications

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group

A model of non‐isothermal degradation of nutrients, pigments and enzymes

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