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Mieke Uyttendaele - One of the best experts on this subject based on the ideXlab platform.

  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Abstract Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's ‘use by’ date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n  = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the ‘use by’ date; 2.5% of the consumers would still consume the product after more than three days past the ‘use by’ date and 4.6% did not consider the ‘use by’ date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the ‘use by’ date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs.

  • Microbial safety and quality of various types of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Abstract Refrigerated Processed Foods of Extended Durability (REPFEDs) are a diverse group of food products. Their production process consists of a variable sequence of different processing steps leading to various types of REPFEDs being introduced to the market. To assure microbial safety, the food industry relies on a combination of mild heat treatment (i.e. pasteurization), appropriate product formulation (i.e. pH, water activity, modified atmosphere packaging, preservatives), cold storage and shelf life limitation. In this paper a classification of REPFED food types is presented and their microbiological safety is evaluated. REPFEDs were classified according (i) to the production process and (ii) to the expected consumer's reheating practices. To evaluate the microbiological safety, historical data on the microbial contamination of REPFEDS were collected from five companies, 706 analyses on the day of production ( T 0 ) and 2912 analyses at the end of shelf life ( T EoS ). Results demonstrated that the microbial safety of the products is overall satisfactory. The number of samples exceeding the acceptable levels for Bacillus cereus/ sulfite reducing Clostridia ( T 0 : 10 3  CFU/g, T EoS : 10 5  CFU/g) was 4.07%/1.94% at T 0 and 2.04%/0.69% at T EoS . None of the samples exceeded the acceptable levels for Listeria monocytogenes ( T 0 : Absent in 25 g, T EoS: max 10 2  CFU/g). In addition the temperature of 38 products was monitored during reheating according to instructions of the manufacturer. The pasteurization values obtained during reheating are very heterogeneous, and only 7 products obtained a P 70 of 2 min throughout the entire product. To assess the effect of reheating on L. monocytogenes a challenge test (including reheating) of paella with L. monocytogenes was performed. This demonstrated that L. monocytogenes can grow up to 0.63 log CFU/g in 6 days at 4 °C and that reheating the paella according to the instructions on the label does not guarantee absence of L. monocytogenes . These findings demonstrate the microbial food safety of the tested REPFEDs is satisfactory, and that producers should not rely on the reheating at consumer level to eliminate L. monocytogenes.

  • Consumer habits and their impact on the food safety of cooked Chilled Foods: results of a survey in Belgium
    2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    The consumer exposure to pathogenic microorganisms due to consumption of cooked Chilled Foods is influenced by the industrial production process and consumer behaviour. A consumer survey was organised to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product’s ‘use by’ date. Of the 874 respondents, over three quarters (77.5%, n=677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of cooked Chilled Foods (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging, the remaining consumers consider a margin of 3 days or more to be acceptable. In addition only half of the consumers fully complied with the reheating instructions on the label. To determine the distribution of the time a cooked Chilled food spends in a consumer fridge, the consumers were asked how frequently they bought these products and how they stored them. This information was used to construct a Time to Consumption (TTC) distribution. This TTC demonstrated that approx. 20% of the products was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. Furthermore, the data shows that frequent consumers are likely to store the products for shorter times. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in cooked Chilled Foods.

  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's 'use by' date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the 'use by' date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the 'use by' date; 2.5% of the consumers would still consume the product after more than three days past the 'use by' date and 4.6% did not consider the 'use by' date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the 'use by' date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs. (C) 2013 Elsevier Ltd. All rights reserved.

  • Assessment of the microbial safety and quality of cooked Chilled Foods and their production process
    International Journal of Food Microbiology, 2012
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Frank Devlieghere, Evy Lahou, Mieke Uyttendaele
    Abstract:

    Abstract Refrigerated processed Foods of extended durability (REPFEDs) are a heterogeneous group of food products. This study assesses the microbial safety and quality along the production process in five REPFED companies. Samples were taken of raw materials (n = 123), intermediate products (n = 123), end products at production day (n = 45) and at end of shelf life (n = 90), food contact surfaces (n = 226) and worker's hands/gloves (n = 92). Samples are analysed for total psychrotrophic aerobic count, aerobic spore count, sulphite reducing Clostridia , Bacillus cereus and Listeria monocytogenes . Both L. monocytogenes and B. cereus were detected on the raw materials. Nine of 72 raw materials tested were positive (in 25 g) for L. monocytogenes and all but one of these raw materials were raw or minimally processed animal products. Three of 123 raw materials contained high counts (> 4 log CFU/g) of B. cereus , all of these samples were dried herbs. During production both food contact surfaces (90/226) and gloves (43/92) contained increased levels of total psychrotrophic aerobic counts (≥ 3 log CFU/25 cm 2 ). This points out a potential source of bacterial recontamination. However, only a four and six of 223 food contact surfaces were positive (per 25 cm 2 ) for L. monocytogenes and B. cereus respectively. None of the gloves sampled contained L. monocytogenes and only 2 sets of gloves were positive for B. cereus . Of the 123 intermediate products tested twelve tested positive for L. monocytogenes (in 25 g) and 5 showed elevated counts of B. cereus (ca. 2.5 log CFU/g). Despite the presence of L. monocytogenes in the raw materials, the production area and in some of the intermediate products, none of the end products were positive for L. monocytogenes and only 9 of 135 samples (6.7%) showed to have low numbers of B. cereus (

Frédéric Carlin - One of the best experts on this subject based on the ideXlab platform.

  • improving quantitative exposure assessment by considering genetic diversity of b cereus in cooked pasteurised and Chilled Foods
    International Journal of Food Microbiology, 2008
    Co-Authors: A L Afchain, Frédéric Carlin, Christophe Nguyenthe, I Albert
    Abstract:

    The natural contamination of Foods with a bacterial pathogen frequently consists of a mixture of strains with their own characteristics of survival, growth potential and virulence. Quantitative Microbial Risk Assessment (QMRA) must account for this genetic diversity to reflect the variability of the pathogen risk and to identify the genetic groups present at key stages of the food pathway. To describe the transmission dynamics of a heterogeneous population of B. cereus, we developed an exposure model that covers a food processing chain from "farm to table". The studied food was a cooked, pasteurised and Chilled courgette puree used as an example of Refrigerated Processed Food of Extended Durability (REPFED). The B. cereus population consists of a continuum of genetic groups ranging from mesophilic and highly heat resistant, to psychrotrophic and moderately-heat resistant ones. At each step in a processing chain comprising cooking, blending, mixing with ingredients providing a secondary contamination, pasteurisation and chilling for several weeks, the prevalence of contaminated units (batches or packages) and the spore load within the units was determined for each genetic group, as well as their proportion to the total B. cereus population in the units. The model predicted that all packages contain mesophilic groups just after partitioning. The addition of mesophilic strains by the ingredients during the process of the courgette puree was an important contribution. At the end of the domestic storage, the model predicted a dominance of the mesophilic groups, while only some psychrotrophic groups were present.

  • Antimicrobial activity of foodborne Paenibacillus and Bacillus spp. against Clostridium botulinum.
    Journal of Food Protection, 2002
    Co-Authors: Hélène Girardin, Christine Albagnac, Claire Dargaignaratz, Christophe Nguyen-the, Frédéric Carlin
    Abstract:

    The saprophytic Paenibacillus and Bacillus spp. found in cooked Chilled Foods may have an effect on the growth of Clostridium botulinum, a major microbiologicalhazard, especially for pasteurized vacuum-packaged products. Culture supernatants of 200 strains of Paenibacillus and Bacillus strains isolated from commercial cooked Chilled Foods containing vegetables were screened for activity against C. botulinum type A, proteolytic type B, and type E strains in a well diffusion assay. Nineteen strains were positive against C. botulinum. Among those, seven Paenibacillus polymyxa strains showed the highest antibotulinal activity and the largest antimicrobial spectrum against C. botulinum strains. The antibotulinal activity was evaluated throughout the growth of a representative strain of the positive P. polymyxa strains. The antimicrobial activity was detected in the culture supernatant from late-log/early stationary phase of the bacteria, which occurred after 7 to 10 days of incubation at 10°C and after 2 to 3 ...

  • screening for clostridium botulinum type a b and e in cooked Chilled Foods containing vegetables and raw material using polymerase chain reaction and molecular probes
    Journal of Food Protection, 2001
    Co-Authors: Agnes Braconnier, Christophe Nguyenthe, Veronique Broussolle, Sylvie Perelle, Patrick Fach, Frédéric Carlin
    Abstract:

    A molecular method was used for the detection of Clostridium botulinum spores of type A, B, and E in commercial cooked and pasteurized vegetable purees and in the raw materials (vegetables and other ingredients). The method allowed the detection of less than 8 spores/g of product for C. botulinum type A, less than 1 spore/g for proteolytic type B, less than 21 spores/g for nonproteolytic type B, and less than 0.1 spore/g for type E. Thirty-seven samples of raw vegetables and ingredients were tested for the presence of C. botulinum type A, B, and E; 88 and 90 samples of vegetable purees were tested, respectively, for the presence of C. botulinum type A and B and for the presence of C. botulinum type E. All samples were negative, suggesting that the prevalence of C. botulinum in these vegetable purees and the raw ingredients is probably low.

  • Research on factors allowing a risk assessment of spore-forming pathogenic bacteria in cooked Chilled Foods containing vegetables: a FAIR collaborative project.
    International Journal of Food Microbiology, 2000
    Co-Authors: Frédéric Carlin, Gary C. Barker, Michael W. Peck, Hélène Girardin, Sandra C. Stringer, Antonio Martínez, Aurea Fernandez, Pablo S. Fernández, William M. Waites, Sara Movahedi
    Abstract:

    Vegetables are frequent ingredients of cooked Chilled Foods and are frequently contaminated with spore-forming bacteria (SFB). Therefore, risk assessment studies have been carried out, including the following: hazard identification and characterisation--from an extensive literature review and expertise of the participants, B. cereus and C. botulinum were identified as the main hazards; exposure assessment--consisting of determination of the prevalence of hazardous SFB in cooked Chilled Foods containing vegetables and in unprocessed vegetables, and identification of SFB representative of the bacterial community in cooked Chilled Foods containing vegetables, determination of heat-resistance parameters and factors affecting heat resistance of SFB, determination of the growth kinetics of SFB in vegetable substrate and of the influence of controlling factors, validation of previous work in complex food systems and by challenge testing and information about process and storage conditions of cooked Chilled Foods containing vegetables. The paper illustrates some original results obtained in the course of the project. The results and information collected from scientific literature or from the expertise of the participants are integrated into the microbial risk assessment, using both a Bayesian belief network approach and a process risk model approach, previously applied to other foodborne hazards.

  • prevalence characterization and growth of bacillus cereus in commercial cooked Chilled Foods containing vegetables
    Journal of Applied Microbiology, 2000
    Co-Authors: Caroline Choma, Frédéric Carlin, Mariehelene Guinebretiere, Philippe Schmitt, Philippe Velge, Per Einar Granum, Christophe Nguyenthe
    Abstract:

    In cooked-Chilled and pasteurized vegetable products, initial numbers of Bacillus cereus were below 10 cfu g−1. Before the appearance of spoilage, numbers reached 6–8 log cfu g−1 at 20 °C and 4–6 log cfu g−1 at 10 °C. Bacillus cereus was not detected in samples stored at 4 °C. Ten percent of strains isolated from the products were able to grow at 5 °C and 63% at 10 °C. Bacillus cereus strains unable to degrade starch, a feature linked to the production of emetic toxin, did not grow at 10 °C and had a higher heat resistance at 90 °C. Using immunochemical assays, enterotoxin was detected in the culture supernatant fluid of 97·5% of the strains. All culture supernatant fluids were cytotoxic but important variations in the level of activity were found. Psychrotrophic isolates of B. cereus were unable to grow in courgette broth at 7 °C whereas they grew in a rich laboratory medium. At 10 °C, these isolates grew in both media but lag time in courgette broth was 20-fold longer than in the rich laboratory medium.

Jeanne-marie Membré - One of the best experts on this subject based on the ideXlab platform.

  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Abstract Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's ‘use by’ date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n  = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the ‘use by’ date; 2.5% of the consumers would still consume the product after more than three days past the ‘use by’ date and 4.6% did not consider the ‘use by’ date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the ‘use by’ date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs.

  • Consumer habits and their impact on the food safety of cooked Chilled Foods: results of a survey in Belgium
    2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    The consumer exposure to pathogenic microorganisms due to consumption of cooked Chilled Foods is influenced by the industrial production process and consumer behaviour. A consumer survey was organised to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product’s ‘use by’ date. Of the 874 respondents, over three quarters (77.5%, n=677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of cooked Chilled Foods (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging, the remaining consumers consider a margin of 3 days or more to be acceptable. In addition only half of the consumers fully complied with the reheating instructions on the label. To determine the distribution of the time a cooked Chilled food spends in a consumer fridge, the consumers were asked how frequently they bought these products and how they stored them. This information was used to construct a Time to Consumption (TTC) distribution. This TTC demonstrated that approx. 20% of the products was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. Furthermore, the data shows that frequent consumers are likely to store the products for shorter times. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in cooked Chilled Foods.

  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's 'use by' date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the 'use by' date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the 'use by' date; 2.5% of the consumers would still consume the product after more than three days past the 'use by' date and 4.6% did not consider the 'use by' date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the 'use by' date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs. (C) 2013 Elsevier Ltd. All rights reserved.

  • A quantitative microbiological risk assessment of Bacillus cereus in cooked Chilled Foods
    2012
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    The risk assessment model consists of eight modules: (1) raw material contamination, (2) contamination during ingredient preparation (3) inactivation during cooking or baking (4) lag time and growth during intermediate storage (5) contamination before packaging (6) partitioning during packaging (7) inactivation during pasteurization and (8) lag time and outgrowth during storage at retail outlet and at consumers’ place. Raw materials (1) were distributed in five groups (e.g. herbs and spices) and the B. cereus contamination was modelled using Bayesian inference based on censored data collected at five CCF companies. This gave a distribution for each group and allowed the input of a simplified recipe. The contamination during ingredient preparation (2) and before packaging (5) was modelled using Bayesian inference based on data gathered at the CCF companies. The inactivation during cooking (3) and pasteurization (6), as well as the partitioning (7) was modelled using existing models. Lag time and growth during intermediate (4) and final (8) storage were modelled using a newly developed model for heat-treated B. cereus spores under refrigeration temperatures. For the storage in the supply chain, the variation in fridge temperatures and time to consumption were taken into account. All eight steps were combined using the @Risk software. The resulting QMRA allowed to estimate the contamination level of a CCF based on the ingredient composition (e.g. 20% starch, etc.) and the processing conditions (e.g. 10 min at 90°C + 3 hours waiting, etc.). Sensitivity analysis shows that the most prominent sources of variability (V) were the D-values of B. cereus (V) and the consumer fridge temperature. In contrast, the main sources of uncertainty were the time to consumption and the lag time model error. This QMRA enables assessing the current risk of CCF and the effect of changes in production process or product formulation. It definitely aids product development and quality improvement. This study was funded by the Federal Public Service of Health, Food Chain Safety and Environment (Contract RT 09/01 MICRORISK).

  • use of sensitivity analysis to aid interpretation of a probabilistic bacillus cereus spore lag time model applied to heat treated Chilled Foods repfeds
    International Journal of Food Microbiology, 2008
    Co-Authors: Jeanne-marie Membré, Denis Kankingyu, Clive De W Blackburn
    Abstract:

    The microbiological safety and quality of REfrigerated Processed Foods of Extended Durability (REPFEDs) relies on a combination of mild heat treatment and refrigeration, sometimes in combination with other inhibitory agents that are not effective when used alone. In this context, the output of a probabilistic model predicting the lag time of heat-treated Bacillus cereus spores under realistic heat-treatment profile and Chilled supply-chain conditions, has been investigated using a sensitivity analysis technique. Indeed, knowing that there was uncertainty in the model (e.g. due to lack of data to build the model input probability density function), the objective of the analysis was to evaluate if the variability associated with some inputs (e.g. the consumers' refrigerator temperature values reported in Europe and US markets were different) had a significant impact on the model output, i.e. on the expected lag time of heat-treated B. cereus spores in REPFEDs. To do so, the uncertainty and variability associated with the various model inputs have been identified and then separated using a second order Monte Carlo decomposition. Concerning the variability, there was a significant difference between the Chilled supply-chains (Europe, US) and between the raw material groups (low, medium or high contamination levels). For example, in the European market, after a heat treatment of 90 °C for 10 min, with a high raw material contamination level, the predicted 5th percentile of the lag time was 17 days, while it was 35 days with a low raw material contamination level. This was confirmed with an ANOVA. The impact of the uncertainty on the lag time has been illustrated graphically by building confidence intervals around its 5th percentile. A sensitivity analysis based upon uncertainty and variability decomposition is clearly a complex and time consuming exercise; however, it provides a greater confidence (greater transparency and better understanding) in the model output when making food safety decisions (e.g. determining the safe shelf-life of REPFEDs).

Line Thorsen - One of the best experts on this subject based on the ideXlab platform.

  • cereulide formation by bacillus weihenstephanensis and mesophilic emetic bacillus cereus at temperature abuse depends on pre incubation conditions
    International Journal of Food Microbiology, 2009
    Co-Authors: Line Thorsen, Birgitte Bjorn Budde, Lars Henrichsen, Torben Martinussen, Mogens Jakobsen
    Abstract:

    Abstract Emetic toxin (cereulide) formation was recently identified in a psychrotolerant species, Bacillus weihenstephanensis [Thorsen, L., Hansen, B.M., Nielsen, K.F., Hendriksen, N.B., Phipps, R.K., Budde, B.B., 2006. Characterization of emetic Bacillus weihenstephanensis is, a new cereulide-producing bacterium. Applied and Environmental Microbiology, 72, 5118–5121.]. Although recent findings indicated B. weihenstephanensis as a cereulide producer only limited information is available regarding environmental conditions affecting cereulide production. In the present study a model agar system was used to compare cereulide production during surface growth of B. weihenstephanensis MC67, and two well known mesophilic cereulide producing Bacillus cereus strains, NC7401 and NS117. Cereulide production was quantified by use of Liquid-Chromatography Mass Spectrometry/Mass Spectrometry. Cereulide production of B. weihenstephanensis MC67 occurred in stationary growth phase, as previously observed for B. cereus , and biomass formation and cereulide formation showed a linear correlation. During incubation at 5 °C for 1, 2 and 3 weeks growth was inhibited and as a consequence no detectable cereulide production occurred for any of the three strains. Similar results were obtained for the mesophilic B. cereus strains when incubated at 8 °C, whereas B. weihenstephanensis MC67 grew to stationary phase and produced 0.002 μg cereulide/cm 2 agar surface in 1 week. Raising the temperature from 5 °C to 25 °C for 24 h after 1 week of incubation resulted in growth to stationary phase and production of variable levels of cereulide. B. weihenstephanensis MC67 produced 6.18 μg cereulide/cm 2 , B. cereus NS117 0.91 μg cereulide/cm 2 and B. cereus NC7401 0.09 μg cereulide/cm 2 . Similar levels of cereulide was produced by the mesophilic strains when raising the temperature from 8 °C (instead of from 5 °C) to 25 °C for 24 h, while a considerably lower level was produced by B. weihenstephanensis MC67 (0.10 μg cereulide /cm 2 ). If the temperature was raised from 5 °C and 8 °C to 25 °C for 24 h after an increased incubation time for 2 and 3 weeks, all three strains produced considerably less cereulide. B. weihenstephanensis MC67 produced 100–6000 times less and the mesophilic B. cereus strains produced 9–40 times less cereulide. These results can partly be explained by differences in the growth at the temperature abuse. Effect of chill storage on cereulide production at temperature abuse has not been investigated previously . Results of the present study indicate that storage at 5 and 8 °C will not lead to emetic intoxications, however the time at, and choice of chill temperature will determine the amount of cereulide produced in a temperature abuse situation. These results are of relevance for the safety of Chilled Foods of extended durability.

  • effect of modified atmosphere and temperature abuse on the growth from spores and cereulide production of bacillus weihenstephanensis in a cooked Chilled meat sausage
    International Journal of Food Microbiology, 2009
    Co-Authors: Line Thorsen, Birgitte Bjorn Budde, Anette Granly Koch, Trine Dano Klingberg
    Abstract:

    Abstract The effect of modified atmosphere packaging (MAP) on the germination and growth of toxin producing psychrotolerant Bacillus spp is not well described. A model agar system mimicking a cooked meat product was used in initial experiments. Incubation at refrigeration temperature of 8 °C for 5 weeks of 26 Bacillus weihenstephanensis including two emetic toxin (cereulide) producing strains showed that B. weihenstephanensis is sensitive to MAP containing CO 2 . The sensitivity to 20% CO 2 was dependent on strain and oxygen level, being increased when oxygen was excluded from the MAP. Growth from spores was observed at the earliest within 2 weeks when 20% CO 2 was combined with 2% O 2 and in 3 weeks when combined with “0”% O 2 (the remaining atmosphere was made up from N 2 ). Results were validated in a cooked meat sausage model for two non-emetic and one emetic B. weihenstephanensis strain. The packaging film oxygen transfer rates (OTR) were 1.3 and 40 ml/m 2 /24 h and the atmospheres were 2% O 2 /20% CO 2 and “0”% O 2 /20% CO 2 . Oxygen availability had a large impact on the growth from spores in the MAP meat sausage, only the most oxygen restricted condition (OTR of 1.3 ml/m 2 /24 h and “0”% O 2 /20 % CO 2 ) inhibited growth of the three strains during 4 weeks storage at 8 °C. Cereulide production was undetectable during storage at 8 °C irrespective of choice of the MAP (quantified by liquid chromatography mass spectrometry/mass spectrometry). MAP storage at 8 °C for 1 and 3 weeks followed by opening of packages and temperature abuse for 1.5 h daily at 20 °C during 1 week resulted in increased cell counts and variable cereulide production in the meat sausage. A pre-history at 8 °C for 1 week in MAP with OTR of 1.3 or 40 ml/m 2 /24 h and 2% O 2 resulted in cereulide concentrations of 0.816 – 1.353 µg/g meat sausage, while a pre-history under the most oxygen restricted condition (OTR of 1.3 ml/m 2 /24 h, “0”% O 2 /20 % CO 2 ) resulted in minimal cereulide production (0.004 µg/g meat sausage) at abuse condition. Extension of MAP storage at 8 °C for 3 weeks followed by abuse resulted in a substantially reduced cereulide production. Data demonstrates that MAP can be used to inhibit growth of a psychrotolerant toxin producing Bacillus spp. during chill storage at 8 °C, and substantially reduce the risk of emetic food poisoning at abuse condition . Results are of relevance for improving safety of ready to eat processed Chilled Foods of extended durability.

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  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Abstract Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's ‘use by’ date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n  = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the ‘use by’ date; 2.5% of the consumers would still consume the product after more than three days past the ‘use by’ date and 4.6% did not consider the ‘use by’ date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the ‘use by’ date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs.

  • Microbial safety and quality of various types of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Abstract Refrigerated Processed Foods of Extended Durability (REPFEDs) are a diverse group of food products. Their production process consists of a variable sequence of different processing steps leading to various types of REPFEDs being introduced to the market. To assure microbial safety, the food industry relies on a combination of mild heat treatment (i.e. pasteurization), appropriate product formulation (i.e. pH, water activity, modified atmosphere packaging, preservatives), cold storage and shelf life limitation. In this paper a classification of REPFED food types is presented and their microbiological safety is evaluated. REPFEDs were classified according (i) to the production process and (ii) to the expected consumer's reheating practices. To evaluate the microbiological safety, historical data on the microbial contamination of REPFEDS were collected from five companies, 706 analyses on the day of production ( T 0 ) and 2912 analyses at the end of shelf life ( T EoS ). Results demonstrated that the microbial safety of the products is overall satisfactory. The number of samples exceeding the acceptable levels for Bacillus cereus/ sulfite reducing Clostridia ( T 0 : 10 3  CFU/g, T EoS : 10 5  CFU/g) was 4.07%/1.94% at T 0 and 2.04%/0.69% at T EoS . None of the samples exceeded the acceptable levels for Listeria monocytogenes ( T 0 : Absent in 25 g, T EoS: max 10 2  CFU/g). In addition the temperature of 38 products was monitored during reheating according to instructions of the manufacturer. The pasteurization values obtained during reheating are very heterogeneous, and only 7 products obtained a P 70 of 2 min throughout the entire product. To assess the effect of reheating on L. monocytogenes a challenge test (including reheating) of paella with L. monocytogenes was performed. This demonstrated that L. monocytogenes can grow up to 0.63 log CFU/g in 6 days at 4 °C and that reheating the paella according to the instructions on the label does not guarantee absence of L. monocytogenes . These findings demonstrate the microbial food safety of the tested REPFEDs is satisfactory, and that producers should not rely on the reheating at consumer level to eliminate L. monocytogenes.

  • Consumer habits and their impact on the food safety of cooked Chilled Foods: results of a survey in Belgium
    2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    The consumer exposure to pathogenic microorganisms due to consumption of cooked Chilled Foods is influenced by the industrial production process and consumer behaviour. A consumer survey was organised to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product’s ‘use by’ date. Of the 874 respondents, over three quarters (77.5%, n=677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of cooked Chilled Foods (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the ‘use by’ date as indicated on the packaging, the remaining consumers consider a margin of 3 days or more to be acceptable. In addition only half of the consumers fully complied with the reheating instructions on the label. To determine the distribution of the time a cooked Chilled food spends in a consumer fridge, the consumers were asked how frequently they bought these products and how they stored them. This information was used to construct a Time to Consumption (TTC) distribution. This TTC demonstrated that approx. 20% of the products was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. Furthermore, the data shows that frequent consumers are likely to store the products for shorter times. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in cooked Chilled Foods.

  • Behaviour of Belgian consumers, related to the consumption, storage and preparation of cooked Chilled Foods
    Food Control, 2013
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Jeanne-marie Membré, Benedikt Sas, Frank Devlieghere, Mieke Uyttendaele
    Abstract:

    Cooked Chilled Foods or Refrigerated and Processed Foods of Extended Durability (REPFEDs) are a heterogeneous group of food products designed for consumer convenience. The consumer exposure to pathogenic microorganisms due to the consumption of REPFEDs is influenced by the industrial production process and by consumer behaviour. A consumer survey was organised and conducted to assess the consumption frequency, storage time, reheating practices and perception of and respect for the product's 'use by' date. The survey was conducted at a local food fair in Belgium with 874 respondents correctly completing the questionnaire. Over three quarters (77.5%, n = 677) had consumed at least one REPFED over the last year. Consumption frequency was the highest between the ages of 18 and 30. Nine out of ten consumers were able to give an acceptable estimate of the shelf life of REPFEDs (e.g. less than four weeks). By contrast, only half of the consumers (53.3%) fully respected the 'use by' date as indicated on the packaging. The majority of the remaining consumers (39.6%) would consume the product until three days past the 'use by' date; 2.5% of the consumers would still consume the product after more than three days past the 'use by' date and 4.6% did not consider the 'use by' date. In addition, only half of the consumers fully complied with the reheating instructions on the label, 36.5% only partially followed these instructions and 13.4% did not follow them at all. Data analysis showed that consumers, who did not respect the 'use by' date, were also less likely to follow the reheating instructions. To determine the distribution of the time a REPFED spends in a consumer fridge, the consumers were asked how frequently they bought REPFEDs and how they stored them. Using this information an attempt was made to construct a time-to-consumption (TTC) distribution. This TTC demonstrated that approx. 20% of REPFEDs was consumed on the day of purchase; about half (52.9%) were consumed within two days of purchase, 75.5% within four days and over 90% during the first week. These short storage times are likely to reduce the exposure to psychrotrophic microorganisms present in REPFEDs. (C) 2013 Elsevier Ltd. All rights reserved.

  • Assessment of the microbial safety and quality of cooked Chilled Foods and their production process
    International Journal of Food Microbiology, 2012
    Co-Authors: Jeff Daelman, Liesbeth Jacxsens, Frank Devlieghere, Evy Lahou, Mieke Uyttendaele
    Abstract:

    Abstract Refrigerated processed Foods of extended durability (REPFEDs) are a heterogeneous group of food products. This study assesses the microbial safety and quality along the production process in five REPFED companies. Samples were taken of raw materials (n = 123), intermediate products (n = 123), end products at production day (n = 45) and at end of shelf life (n = 90), food contact surfaces (n = 226) and worker's hands/gloves (n = 92). Samples are analysed for total psychrotrophic aerobic count, aerobic spore count, sulphite reducing Clostridia , Bacillus cereus and Listeria monocytogenes . Both L. monocytogenes and B. cereus were detected on the raw materials. Nine of 72 raw materials tested were positive (in 25 g) for L. monocytogenes and all but one of these raw materials were raw or minimally processed animal products. Three of 123 raw materials contained high counts (> 4 log CFU/g) of B. cereus , all of these samples were dried herbs. During production both food contact surfaces (90/226) and gloves (43/92) contained increased levels of total psychrotrophic aerobic counts (≥ 3 log CFU/25 cm 2 ). This points out a potential source of bacterial recontamination. However, only a four and six of 223 food contact surfaces were positive (per 25 cm 2 ) for L. monocytogenes and B. cereus respectively. None of the gloves sampled contained L. monocytogenes and only 2 sets of gloves were positive for B. cereus . Of the 123 intermediate products tested twelve tested positive for L. monocytogenes (in 25 g) and 5 showed elevated counts of B. cereus (ca. 2.5 log CFU/g). Despite the presence of L. monocytogenes in the raw materials, the production area and in some of the intermediate products, none of the end products were positive for L. monocytogenes and only 9 of 135 samples (6.7%) showed to have low numbers of B. cereus (