Quantitative description of Listeria monocytogenes inactivation kinetics with temperature and water activity as the influencing factors; model prediction and methodological validation on dynamic data

Valdramidis, Vasilis; Geeraerd, A.H.; Gaze, J.E.; Kondjoyan, Alain; Boyd, Andrew R.; Shaw, Hannah L.; Impe, Jan Van

doi:10.1016/j.jfoodeng.2005.05.025

Cited by 47 publications

(35 citation statements)

References 22 publications

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“…The large unreliability in the estimated z value (Table 2) could be attributed to other environmental factors that are directly related to the induced microbial heat resistance of the surface attached cells. For example, previous studies revealed that the z value can be subdivided over other environmental factors besides the temperature, like water activity, pH and described by z aw , z pH , respectively (Gaillard et al 1998;Valdramidis et al 2006). Further investigation into the causes and effects of the heat resistance of surface attached cells could result in another subdivision of the currently used z value.…”

Section: Prediction Of the Microbial Inactivation Kinetics Of Surfacementioning

confidence: 99%

Quantitative Evaluation of Thermal Inactivation Kinetics of Free-Floating Versus Surface-Attached Listeria innocua Cells

Valdramidis

Péroval²,

Portanguen³

et al. 2007

Food Bioprocess Technol

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Surface pasteurization is one of the decontamination treatments that can contribute to better preservation of meat products retaining most of their quality characteristics relatively intact if compared with the raw products. The current research compares the kinetics of free-floating and surface attached Listeria innocua cells by using integrated microbial and heat transfer modelling approaches. Surface pasteurization treatments are applied on a (abiotic) Teflon® model system in a novel steam surface decontamination rig. The experimental set-up prevented following four technological aspects to occur, (1) cold purge migration to the surface during the heating process, (2) inactivation kinetics of a cocktail of microbes, (3) protective effect of food components, and (4) physical distribution of bacteria throughout the depth of the product skin. Microbial load predictions are performed based on the inactivation parameters obtained during free-floating cell experiments. These predictions, when compared with the microbial data of the surface treatments, prove that the surface attached cells were much more heat resistant, despite the experimental set-up preventing the aforementioned (technological) events to occur. Indeed, surface attached cells can have different physiological/phenotypical/genetical characteristics, such as cell aggregations, colony formations, presence of flagella. In a final step, three techniques are implemented to evaluate mathematically the kinetics of the surface attached cells. Overall, this research's significance is lying in the quantitative assessment of microbial heat resistance. The technological reasons underlying the increased microbial heat resistance on biotic and abiotic surfaces should be reevaluated, taking into account possible physiological/ phenotypical/genetical characteristics.

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Section: Prediction Of the Microbial Inactivation Kinetics Of Surfacementioning

confidence: 99%

Quantitative Evaluation of Thermal Inactivation Kinetics of Free-Floating Versus Surface-Attached Listeria innocua Cells

Valdramidis

Péroval²,

Portanguen³

et al. 2007

Food Bioprocess Technol

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“…The results of all the microbial death experiments have been used by the Department of Food and Microbial Technology, Katholieke Universiteit Leuven (KUL) in Belgium to create mathematical relationships between temperature, a w and bacterial death (Valdramidis et al, 2005).…”

Section: Produce Relationships Between Microbial Death and Measured Tmentioning

confidence: 99%

Predicting the reduction in microbes on the surface of foods during surface pasteurisation—the ‘BUGDEATH’ project

James

Evans

2006

Journal of Food Engineering

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The prime objective of the BUGDEATH project was to produce accurate predictive models of the reductions in microbial numbers that can be achieved on the surface of foods during surface pasteurisation processes. These models will enable a wide range of food manufacturers to design more effective and efficient surface pasteurisation treatments than can be produced with current microbial death models and data.During the project test apparatus was built and delivered to partners that can create ÔrapidÕ heating processes, where surface temperatures rise from 5 to 100°C in less than 1 min, can be held at a set temperature and then cooled rapidly. Slower heating and cooling processes can be carried out to compare the effects of heating and cooling times on bacterial death. Both dry and wet (steam) heating were possible.The partners carrying out microbiological trials used the test apparatus. Bacterial death was monitored by viable counts and also by specialist techniques including use of a low light-level camera and bacteria tagged with lux genes. Using organisms which have been treated by adding lux genes to make them glow (bioluminescence), and applying them to the food surface to be treated, the scientists can quickly measure changes taking place in the bacteria. If the bioluminescence fades when the food is treated then the process is effective. The bacteria glow brightly when healthy, fade when expiring and stop glowing the moment they stop metabolizing.The major aim of the project was to create a user-friendly heat transfer and microbial death model. These models were validated against published data and data provided by the partners. The programme simulates inactivation kinetics of microorganisms on food surfaces, during dry and wet pasteurisation treatments under constant and time-varying temperature conditions. On the basis of selection of a heating regime of the medium, the programme allows accurate prediction of food surface temperature and simulates the microbial load content along the whole process time. Input data and simulated values can be visualised in graphics or data tables. Printing, exporting and saving file options are available. It includes a useful database of foods (i.e. beef and potato) and related thermal properties, microorganisms (i.e. Listeria monocytogenes and Salmonella) and corresponding inactivation kinetic parameters.The software can be used to simulate results during pasteurisation treatments. The pull off simulations can be valuable to a wide variety of companies in the food industry for developing appropriate and safe processes. The software has also the potential of being exploited for educational purposes.The project involved 8 partners from 5 countries and was coordinated by FRPERC from the University of Bristol, UK. As part of the project the research team recruited an Industrial Advisory Group (IAG) to ensure that the project was relevant and useful to the European food industry.

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“…Based on the characteristics of the heating regime, the surface temperature can be estimated. As shown in Valdramidis et al (2005b), acceptable predictions of the microbial content at food surface can be attained under certain circumstances. These studies were based on the researching effort of partners of the European project BUGDEATH (QLRT-2001-01415), with FRPERC as the coordinator.…”

Section: Introductionmentioning

confidence: 98%

Integrated approach on heat transfer and inactivation kinetics of microorganisms on the surface of foods during heat treatments—software development

Gil¹,

Pereira²,

Brandão³

et al. 2006

Journal of Food Engineering

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The objective of this work was to create a software application (Bugdeath 1.0) for the simulation of inactivation kinetics of microorganisms on the surface of foods, during dry and wet pasteurisation treatments. The program was developed under the Real Basic Ó 5.2 application, and it is a user-friendly tool. It integrates heat transfer phenomena and microbial inactivation under constant and time-varying temperature conditions. On the basis of the selection of a heating regime of the medium, the program predicts the food surface temperature and the change in microbial load during the process. Input data and simulated values can be visualised in graphics or data tables. Printing, exporting and saving file options are also available. Bugdeath 1.0 includes also a useful database of foods (beef and potato) and related thermal properties, microorganisms (Salmonella and Listeria monocytogenes) and corresponding inactivation kinetic parameters. This software can be coupled to an apparatus developed under the scope of the European Project BUGDEATH (QLRT-2001-01415), which was conceived to provide repeatable surface temperature-time treatments on food samples. The program has also a great potential for research and industrial applications.

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Quantitative description of Listeria monocytogenes inactivation kinetics with temperature and water activity as the influencing factors; model prediction and methodological validation on dynamic data

Cited by 47 publications

References 22 publications

Quantitative Evaluation of Thermal Inactivation Kinetics of Free-Floating Versus Surface-Attached Listeria innocua Cells

Quantitative Evaluation of Thermal Inactivation Kinetics of Free-Floating Versus Surface-Attached Listeria innocua Cells

Predicting the reduction in microbes on the surface of foods during surface pasteurisation—the ‘BUGDEATH’ project

Integrated approach on heat transfer and inactivation kinetics of microorganisms on the surface of foods during heat treatments—software development

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