Thermal inactivation of bacteria—a new predictive model for the combined effect of three environmental factors: temperature, pH and water activity

Cerf, O.; Davey, K. G.; Sadoudi, Abdelkrim

doi:10.1016/0963-9969(96)00039-7

Cited by 59 publications

(33 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, several workers have demonstrated that the effect of the water activity of the heating medium depended on the treatment temperature; for example, in Staphylococcus epidermidis (39) or Listeria monocytogenes (37), the protective effect of decreasing water activity is more pronounced at a higher treatment temperature, while the opposite trend was observed for Staphylococcus aureus (38). A few predictive models describing the effect of the water activity of the heating medium on the heat resistance of spores were developed (8,18,31).…”

mentioning

confidence: 99%

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Coroller¹,

Leguérinel²,

Mafart³

2001

Appl Environ Microbiol

View full text Add to dashboard Cite

Spores of Bacillus cereus were heated and recovered in order to investigate the effect of water activity of media on the estimated heat resistance (i.e., the D value) of spores. The water activity (ranging from 0.9 to 1) of the heating medium was first successively controlled with three solutes (glycerol, glucose, and sucrose), while the water activity of the recovery medium was kept near 1. Reciprocally, the water activity of the heating medium was then kept at 1, while the water activity of the recovery medium was controlled from 0.9 to 1 with the same depressors. Lastly, in a third set of experiments, the heating medium and the recovery medium were adjusted to the same activity. As expected, added depressors caused an increase of the heat resistance of spores with a greater efficiency of sucrose with respect to glycerol and glucose. In contrast, when solutes were added to the recovery medium, under an optimal water activity close to 0.98, a decrease of water activity caused a decrease in the estimated D values. This effect was more pronounced when sucrose was used as a depressor instead of glycerol or glucose. When the heating and the recovery media were adjusted to the same water activity, a balancing effect was observed between the protective influence of the solutes during heat treatment and their negative effect during the recovery of injured cells, so that the overall effect of water activity was reduced, with an optimal value near 0.96. The difference between the efficiency of depressors was also less pronounced. It may then be concluded that the overall protective effect of a decrease in water activity is generally overestimated.It has been recognized that the heat resistance of bacterial spores depends on the medium in which the spores are heated. The maximum thermostability of most microorganisms was found in the range of between 0.2 and 0.4 water activity (1,3,27,28,29). In typical ranges of water activities which are found in foodstuffs (a w Ͼ 0.8), the heat resistance of microorganisms generally increases at decreasing water activities. However, the apparent effect of the water activity of the medium on spores or vegetative cells is complicated by the specific effect of solutes which are used as depressors. It is generally agreed that the occurrence of such solutes in the medium reduces the heat resistance of microorganisms. This antagonism between the protective effect of an increase in water activity and the opposite specific effect of depressors can explain conflicting data from various authors.The influence of salt on the thermostability of microorganisms is disputed and depends on the heated type of microorganism. Some authors found no effect of the sodium chloride concentration on the heat resistance of bacteria (9,29,32,42). Others observed a reduced heat resistance of microorganisms at increasing salt concentrations (7,12,22,23). On the contrary, a protective effect of salt was found in several studies (6,14,26,35,38,39,40). Corry (14) deduced from his data that sodium chloride had a therm...

show abstract

mentioning

confidence: 99%

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Coroller¹,

Leguérinel²,

Mafart³

2001

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…Nevertheless, unstructured, unsegregated growth models have been shown to effectively describe the combined effects of a time-invariant suboptimal pH and water activity on specific growth rate (Cerf et al, 1996;Kalathenos et al, 1995;McMeekin et al, 1993;Presser et al, 1997). When growth medium properties are assumed to remain constant, predictive models can also accurately forecast lag times observed in batch reactors (Baranyi et al, 1993;McMeekin et al, 1993).…”

Section: Introductionmentioning

confidence: 97%

Growth ofLeuconostoc mesenteroides NRRL-B523 in an alkaline medium: Suboptimal pH growth inhibition of a lactic acid bacterium

Wolf

Fogler

2004

Biotechnol. Bioeng.

View full text Add to dashboard Cite

Bacterial profile modification (BPM), a form of tertiary oil recovery, diverts water from the water-flooded high-permeability zone into the oil-bearing low-permeability zone. During field use, exopolymer-producing bacteria plug the high-permeability zone only in the immediate vicinity of the injection point (the near-well bore region). For effective BPM the plug must penetrate far into the formation. Slowing the specific growth rate, lengthening the lag phase, and slowing the polymerization rate are techniques that can prolong the onset of biopolymer gelation and extend the depth of the biological plug. In batch experiments, the growth of Leuconostoc mesenteroides NRRL-B523 was inhibited by the synergistic effects of high substrate loading and an alkaline pH. Exponential growth was delayed up to 190 h. It was observed that cell division was significantly retarded until the medium pH, reduced by the acid byproducts of fermentation, reached a critical value of 6.79 +/- 0.06. A mathematical model was developed to describe the relationship between specific growth rate, lag time, and medium pH.

show abstract

“…A five parameter model was proposed by Cerf et al (1996), including an extension of the Davey"s model with the a w term:…”

Section: T T Ph Ph Dd Zzmentioning

confidence: 99%

“…The Arrhenius model has been used for describing the kinetic behaviour of E. coli as a function of temperature, pH and a w (Cerf et al, 1996).…”

Section: Bigelow Model (Linear Model)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

View full text Add to dashboard Cite

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...

show abstract

Thermal inactivation of bacteria—a new predictive model for the combined effect of three environmental factors: temperature, pH and water activity

Cited by 59 publications

References 14 publications

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Growth ofLeuconostoc mesenteroides NRRL-B523 in an alkaline medium: Suboptimal pH growth inhibition of a lactic acid bacterium

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

Contact Info

Product

Resources

About