Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Fermented foods : Products of science and craftsmanship
    Smid, E.J. - \ 2015
    Wageningen : Wageningen University, Wageningen UR - ISBN 9789462573710 - 20
    fermentation - microorganisms - food microbiology - fermented foods - fermentation products - public speeches - fermentatie - micro-organismen - voedselmicrobiologie - gefermenteerde voedingsmiddelen - fermentatieproducten - openbare redes
    Inaugural lecture upon taking up the post of Personal Professor of Food Microbiology at Wageningen University on 11 June 2015. 'Microbial cultures deliver the typical characteristics of fermented food products through their metabolic activity, by secretion of enzymes in the food matrix and by their particular growth and survival behaviour. Knowledge of the structural complexity and population dynamics provides explanations for compositional stability and overall performance of such cultures. Especially, insight into microbial interactions delivers new design rules for robust composite starter cultures with predictable and desirable industrial performance.'
    The Impact of Food Bioactives on Health: in vitro and ex vivo models
    Verhoeckx, K. ; Cotter, P. ; Lopez-Exposito, I. ; Lea, T. ; Mackie, A. ; Requena, T. ; Swiatecka, D. ; Wichers, H.J. - \ 2015
    Zeist : Springer International Publishing - ISBN 9783319157917 - 338
    bioactieve verbindingen - voedselwetenschappen - fysiologie - voedselmicrobiologie - voedsel - gezondheid - bioactive compounds - food sciences - physiology - food microbiology - food - health
    “Infogest” (Improving Health Properties of Food by Sharing our Knowledge on the Digestive Process) is an EU COST action/network in the domain of Food and Agriculture that will last for 4 years from April 4, 2011. Infogest aims at building an open international network of institutes undertaking multidisciplinary basic research on food digestion gathering scientists from different origins (food scientists, gut physiologists, nutritionists…). The network gathers 70 partners from academia, corresponding to a total of 29 countries. The three main scientific goals are: Identify the beneficial food components released in the gut during digestion; Support the effect of beneficial food components on human health; Promote harmonization of currently used digestion models Infogest meetings highlighted the need for a publication that would provide researchers with an insight into the advantages and disadvantages associated with the use of respective in vitro and ex vivo assays to evaluate the effects of foods and food bioactives on health. Such assays are particularly important in situations where a large number of foods/bioactives need to be screened rapidly and in a cost effective manner in order to ultimately identify lead foods/bioactives that can be the subject of in vivo assays. The book is an asset to researchers wishing to study the health benefits of their foods and food bioactives of interest and highlights which in vitro/ex vivo assays are of greatest relevance to their goals, what sort of outputs/data can be generated and, as noted above, highlight the strengths and weaknesses of the various assays. It is also an important resource for undergraduate students in the ‘food and health’ arena.
    Zoektocht naar fermentatieprocessen voor producten met minder zout
    Smid, E.J. - \ 2015
    Wageningen UR
    voedselmicrobiologie - fermentatie - houdbaarheid (kwaliteit) - voedseltechnologie - zout - smaak - voeding en gezondheid - food microbiology - fermentation - keeping quality - food technology - salt - taste - nutrition and health
    De fermentatie van verse plantaardige of dierlijke producten geeft extra smaak aan voedsel en verlengt de houdbaarheid. Het proces vergt echter vaak veel zout en daarvan krijgt de westerling al veel te veel binnen. In zijn inaugurele rede bij de aanvaarding van het persoonlijk hoogleraarschap Levensmiddelenmicrobiologie aan Wageningen University gaat prof. Eddy Smid op zoek naar alternatieve, ‘natriumarme’ fermentatieprocessen die de gezondheid ten goede komen.
    Handbook of Indigenous Foods Involving Alkaline Fermentation
    Sarkar, P.K. ; Nout, M.J.R. - \ 2014
    Boca Raton, FL : CRC Press (Fermented Foods and Beverages Series ) - ISBN 9781466565302 - 629
    fermentation - fermented foods - foods - food microbiology - food preservation - food products - food quality - beverages - fermentatie - gefermenteerde voedingsmiddelen - voedingsmiddelen - voedselmicrobiologie - voedselbewaring - voedselproducten - voedselkwaliteit - dranken
    This book details the basic approaches of alkaline fermentation, provides a brief history, and offers an overview of the subject. The book discusses the diversity of indigenous fermented foods involving an alkaline reaction, as well as the taxonomy, ecology, physiology, and genetics of predominant microorganisms occurring in AFFs. Presented in nine chapters, the book explains how microorganisms or enzymes transform raw ingredients into AFFs. It discusses the safety aspects of AFFs, and considers the challenges associated with the technological aspects in modernizing AFFs. It stresses the significance of the microbiological and biochemical processes in the fermentations, as well as the factors that influence the development of the characteristic microbiota, and the biochemical and organoleptic changes induced by them. It also proposes solutions, discusses the value of AFFs and related dominant microorganisms, and assesses the future of AFFs. The authors highlight commonly known foods and beverages of plant and animal origin. They provide insight into the manufacture, chemical and microbiological composition, processing, and compositional and functional modifications taking place as a result of microbial and enzyme effects. The text examines safety, legislation, traditional and industrialized processes, as well as new product development, and opportunities for developing commodities from Africa, Asia, Europe, Latin America, and the Middle East. In addition, it also assesses the value of food processing by-products, biotechnology, and engineering of solid-state processes, modern chemical and biological analytical approaches to safety, and health and consumer perception.
    Intervention methods to control the transmission of noroviruses and other enteric and respiratory viruses
    Tuladhar, E. - \ 2014
    Wageningen University. Promotor(en): Marcel Zwietering, co-promotor(en): E. Duizer; Rijkelt Beumer. - Wageningen : Wageningen University - ISBN 9789462571129 - 163
    norovirus - gastro-enteritis - uitbraken (ziekten) - ziekteoverdracht - voedselbesmetting - ademhalingsziekten - voedselmicrobiologie - norovirus - gastroenteritis - outbreaks - disease transmission - food contamination - respiratory diseases - food microbiology

    Intervention methods to control the transmission of noroviruses and other enteric and respiratory viruses

    Era Tuladhar


    Human noroviruses are the leading cause of acute and outbreak associated gastroenteritis worldwide. The outbreaks occur often in hospitals, nursing homes, health care centers as well as in individual homes. Due to the high number of outbreaks and frequency of infection, the burden of disease is high. The virus transmission takes place from person to person directly through the fecal oral route or indirectly through contaminated surfaces or consumption of contaminated food. This study aimed to investigate methods to reduce the burden of disease caused by norovirus and focuses on reducing the transmission through hands and contaminated surfaces. Besides human norovirus, other enteric and respiratory viruses are also transmitted through these routes and were included in the study. Enteric viruses included in the study were human norovirus GI.4 and GII.4, poliovirus Sabin1, rotavirus SA11, parechovirus 1 and murine norovirus 1 (MNV1). The respiratory viruses were adenovirus type 5 and influenza A (H1N1) virus. These viruses can contaminate food through food handler-related contamination. Heating and pasteurizing is a commonly used method for inactivation of microorganisms in food. Heating at commonly used temperatures of 56°C and 73°C showed that thermo-stability of parechovirus and influenza virus was found to be similar to that of proven foodborne viruses and heating at 73°C for 3 min is sufficient to reduce the infectivity of the tested viruses > 4 log10. Not only food, contaminated hands can also transfer viruses to different surfaces, which are then sources of further transmission of the viruses. Cleaning and disinfection of contaminated surfaces are common intervention methods used in health care and kitchen facilities. The enteric and respiratory viruses showed varying susceptibility to cleaning and disinfection procedures applied. Data on infectious doses and transfer efficiencies was used to estimate a target level to which the residual contamination should be reduced and it was found that a single wipe with liquid soap followed by a wipe with 250 ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested. Spot disinfection by 1000 ppm chlorine solution after wiping with liquid soap was sufficient to reduce the genomic copies of human norovirus GI.4 and GII.4 (> 5 log10 PCRU) completely within 10 min. In addition to manual cleaning and disinfection, non-touch disinfection of contaminated surfaces by vaporized hydrogen peroxide disinfection at 127 ppm for 1 h, as approved disinfection in the Netherlands for hospitals and health care centers, is effective against poliovirus Sabin 1, rotavirus SA11, adenovirus type 5 and MNV1 on stainless steel, framing panel (> 4 log10 infectivity reduction) and gauze (> 2 log10 infectivity reduction). Beside non-touch disinfection, immobilized biocidals have been tested for disinfection of contaminated surfaces. Immobilized quaternary ammonium compound coatings were virucidal against the influenza virus within 2 min but no virucidal effect against poliovirus was found in 6 h. Thus the coating can be used against the influenza A virus to prevent the transmission through frequently touched sites but not for non-enveloped viruses. Our study demonstrated that a norovirus contaminated hand can transfer the viruses to different surfaces, including food, even after the virus is dried. As an intervention method to prevent the transmission of the virus, washing hands with soap and water (> 5 log10 PCRU reduction) is better than using alcohol based hand disinfectants in removing noroviruses from hands.

    This research has delivered new insights in methods to reduce transmission of human norovirus and produced comparative quantitative data on intervention methods to control transmission of other enteric and respiratory viruses. The study has additionally contributed to a better understanding of human norovirus transmission intervention efficiency. The new insights allow for the development of science based guidelines to control norovirus and other enteric and respiratory viruses in outbreak settings and thus help to reduce the burden of illness caused by these viruses.

    Physiological and molecular adaptations of Lactococcus lactis to near-zero growth conditions
    Ercan, O. - \ 2014
    Wageningen University. Promotor(en): Michiel Kleerebezem, co-promotor(en): Eddy Smid. - Wageningen : Wageningen University - ISBN 9789462570719 - 206
    lactococcus lactis - adaptatiefysiologie - voedselmicrobiologie - groeitempo - groeispanning - transcriptomica - metabolomica - lactococcus lactis - adaptation physiology - food microbiology - growth rate - growth stress - transcriptomics - metabolomics

    Lactococcus lactis is an important lactic acid bacteria (LAB) species that is used for the manufacture of dairy products, such as cheese, buttermilk, and other fermented products. The predominant function of this bacterium in dairy fermentation is the production of lactic acid, as its major fermentation end-product that contributes to preservation and microbial safety of the product. Moreover, L. lactis is frequently encountered in natural ecosystems such as in (rotting) plant material.

    Due to restricted energy source availability, natural microbial communities commonly live in a situation that can be characterized as ‘hunger’, which is different from strict nutrient-starvation. As a consequence, environmental microbes commonly grow at very low-growth rates as compared to laboratory cultures. Analogously, microorganisms can experience such nutrient-poor conditions in diverse industrial fermentation applications. For example, LAB encounter extreme low or no energy source availability during the extended ripening process of cheeses or dry sausages, which can take months. Despite these harsh environmental conditions, many LAB are able to remain viable in these processes for months and sustain a low-level metabolic activity, which plays an important role in their contribution to flavor and aroma formation in the product matrix.

    In this thesis, the quantitative physiology of L. lactis at near-zero specific growth rates was studies, employing both metabolic and genome-wide transcriptome studies in an experimental set-up of carbon-limited retentostat cultivation. Chapter 2 describes how retentostat cultivation enables uncoupling of growth and non-growth related processes in L. lactis, allowing the quantitative analysis of the physiological adaptations of this bacterium to near-zero growth rates. In chapter 3, transcriptome and metabolome analyses were integrated to understand the molecular adaptation of L. lactis to near-zero specific growth rate, and expand the studies in chapter 2 towards gene regulations patterns that play a profound role in zero-growth adaptation. Chapter 4 describes the enhanced robustness to several stress conditions of L. lactis after its adaptation to extremely low-specific growth rate by carbon-limited retentostat cultivation. In this chapter correlations were modelled that quantitatively and accurately describe the relationships between growth-rate, stress-robustness, and stress-gene expression levels, revealing correlation coefficients for each of the varieties involved. Chapter 5 evaluates the distinction between the transcriptome responses to extended carbon-limited growth and severe starvation conditions, where the latter condition was elicited by switching off the medium supply of the retentostat cultures described in chapter 1. Chapter 6 highlights the comparison of the physiological and molecular adaptations of industrially important microorganisms towards carbon-limited retentostat conditions. In conclusion, this thesis describes the quantitative physiological, metabolic, and genome-wide transcriptional adaptations of L. lactis at near-zero specific growth rates induced by carbon source limited retentostat cultivation, and compares these molecular adaptations to those elicited by strict carbon-starvation conditions.

    The limits of testing for microbiological food safety
    Joosten, H.M.L.J. - \ 2014
    Wageningen : Wageningen University - ISBN 9789461737939 - 24
    voedselveiligheid - voedselmicrobiologie - microbiële besmetting - voedselanalyse - kwaliteitscontroles - food safety - food microbiology - microbial contamination - food analysis - quality controls
    Impact of sorbic acid and other mild preservation stresses on germination and outgrowth of Bacillus cereus spores
    Melis, C.C.J. van - \ 2013
    Wageningen University. Promotor(en): Tjakko Abee, co-promotor(en): Masja Nierop Groot. - Wageningen : Wageningen University - ISBN 9789461737755 - 138
    bacillus cereus - sorbinezuur - behoud - kieming - kiemremmers - groei - voedselbewaring - voedselmicrobiologie - bacillus cereus - sorbic acid - preservation - germination - germination inhibitors - growth - food preservation - food microbiology

    Weak organic acids such as sorbic acid, lactate, and acetic acid are widely used by the food industry as preservatives to control growth of micro-organisms. With the current trend towards milder processing of food products, opportunities arise for spore-forming spoilage and pathogenic microorganisms such as Bacillus cereus, that may survive the use of milder heating regimes. Dormant spores produced by B. cereus can survive processing conditions and their subsequent outgrowth increases the risk of premature spoilage and food safety issues. As a consequence, the use of additional preservation hurdles, such as acidification with weak organic acid additives to ensure the quality and safety of a product is important. Sorbic acid is widely used as an antimicrobial compound because of its strong inhibitory properties against bacteria and other spoilage organisms. Its effectivity has also been ascribed to its hydrophobic character, resulting in an additional mode of action not observed with other less lipophilic organic acids such as lactic acid and acetic acid. In this project the impact of sorbic acid on spore germination and outgrowth was studied at transcriptome level and was linked to the distinct phenotypic responses observed for spores exposed to different levels of sorbic acid. The various stages of spore germination and outgrowth could be recognized by distinct gene expression profiles representing either the germination phase, transition state between germination and outgrowth or outgrowing cells, respectively. A subset of genes was specifically expressed in sorbic acid-exposed germinating spores and included functions related to cell envelope, (multi) drug transporters and amino acid metabolism. At high concentrations of sorbic acid (3mM of the undisssociated form, HSA), nutrient-induced germination of B. cereus ATCC 14579 spores was completely blocked. This blockage was shown to be reversible and could be bypassed by known non-nutrient triggers that activate spores in a receptor-independent way, pointing to a possible interference of HSA with the signaling event between germinant receptors and proposed SpoVA-channels, possibly by accumulation into the spore’s inner membrane. Additional experiments with other inhibiting compounds, including organic acids and their structurally similar alcohol counterparts, showed that the lipophilic properties are an important determinant of its efficacy to block germination. Building on current knowledge on the interaction of germination-relevant protein clusters, we discuss a hypothetical model on the mode of action of sorbic acid and other short-chain lipophilic compounds in germination inhibition of B. cereus spores. In addition to the interference or even blockage of germination, sorbic acid may increase outgrowth heterogeneity when applied at lower concentrations (0.25-1.5 mM) that still allow outgrowth. The first stages of outgrowth were shown to specifically occur heterogeneously when spores were exposed to multiple stresses simultaneously. Heterogeneity effects were most pronounced for combined stress-effects where heat-treated spores were also exposed to low pH stress. Under these conditions, a large subpopulation of spores was delayed between initial germination and swelling and further outgrowth. For the food producing industry, it would be desirable to have reliable parameters to predict the behavior of surviving spores in a food product. Data presented in this thesis show that germination rate is not a good predictor for outgrowth heterogeneity when applied as a single indicator. In conclusion, the work described in this thesis strive to obtain a better understanding on the impact that preservation stresses, including (sorbic) acid stress, have on the germination and outgrowth (heterogeneity) of B. cereus spores. The results obtained in this project may contribute to the rational design of new concepts for improved food preservation and safety.

    Hoe?Zo! Radio
    Zwietering, Marcel - \ 2012
    food microbiology - food safety - keeping quality - storage life - food wastage - irradiation
    Levensmiddelenmicrobiologie en zout : zout als conserveermiddel in historisch perspectief: is veiligheid een belemmering om zout te verlagen
    Zwietering, Marcel - \ 2012
    salt - nutrition and health - food technology - food microbiology - food safety - sodium chloride - reduction
    Campylobacter jejuni: een hardnekkige volhouder (interview met L. Verhoeff-Bakkenes)
    Verhoeff-Bakkenes, L. - \ 2012
    campylobacter jejuni - growth - survival - infectivity - bacterial diseases - risk assessment - food microbiology
    Tools for microbiological risk assessment
    Bassett, J. ; Nauta, M. ; Lindqvist, R. ; Zwietering, M.H. - \ 2012
    Belgium : ILSI (ILSI Europe report series ) - ISBN 9789078637349 - 40
    voedselmicrobiologie - risicoschatting - gezondheidsgevaren - computer software - onzekerheidsanalyse - voorspellen - food microbiology - risk assessment - health hazards - uncertainty analysis - forecasting
    Distributions of microorganisms in foods and their impact on food safety
    Jongenburger, I. - \ 2012
    Wageningen University. Promotor(en): Marcel Zwietering; Leon Gorris, co-promotor(en): Martine Reij. - S.l. : s.n. - ISBN 9789461732071 - 208
    micro-organismen - distributie - voedingsmiddelen - voedselveiligheid - voedselmicrobiologie - representatieve monstername - flesvoedingsamenstelling - enterobacter sakazakii - microorganisms - distribution - foods - food safety - food microbiology - representative sampling - infant formulae - enterobacter sakazakii

    The physical distributions of pathogens in foods influence the likelihood that a food product will cause illness, but knowledge about the physical distribution of microorganisms in foods and especially the heterogeneity therein is scarce. This Ph.D. research aims to increase the knowledge of microbial distributions in foods and therewith to provide better insights in their impact on public health and food safety management activities.

    The research covers both theoretical investigations and practical experiments, focusing on powdered infant formula (PIF) as a suitable model product and the opportunistic pathogen Cronobacter spp. as a relevant microorganism in the practical experiments. The impact of spatial distributions of microorganisms, like homogeneous or more clustered distributions, on public health was investigated. Infrequent high doses were shown to mainly determine the probability of illness and also to dominate the arithmetic mean (mean of the counts) expressing the level of microorganisms present. The distribution of Cronobacter spp. in two industrial batches of PIF (a recalled batch and a reference batch) was quantified in detail. Additionally, batches of PIF on lab scale with well-mixed and localised contaminations of Cronobacter sakazakii were enumerated. In the recalled batch, the sample units were taken in the course of the filling time and the results showed that Cronobacter spp. were heterogeneously distributed. On local-scale, clusters of cells varying between 3 and 560 cells per cluster were present sporadically. Discrete and continuous statistical distributions were compared to model the enumeration data of the industrial and laboratory scale batches. Batches with low counts including zeros were fitted best by the Poisson-Lognormal distribution and Negative Binomial distribution. According to criteria proposed to compare the suitability of statistical distributions to model microbial distributions in foods, these two distributions had already been selected to be the most suitable candidates. Furthermore, the performances of random and systematic sampling ware compared to detect a localised contamination in a batch of food. Our calculations showed that systematic sampling rather than random sampling improved the sampling performance. Moreover, taking many small sample units systematically increased the probability to detect the localised contamination. Another systematic sampling strategy evaluated was stratified random sampling. Using the enumeration data of the recalled batch, stratified random sampling appeared to improve the detection probability of Cronobacter spp. as compared to random sampling. Generally, taking more and smaller sample units, while keeping the total sampling weight constant, improved the performance of the sampling plans.

    The insights obtained in this thesis are considered to be relevant to a wide variety of dry products and to an extent also to other structured foods. They should be of use to food business operators to improve sampling and testing to verify control of their operation as well as to assess compliance of final products with food safety standards and guidelines before marketing. The results may equally be useful to governmental bodies setting and enforcing food safety standards (such as microbiological criteria) and conducting microbiological risk assessment.

    Campylobacter jejuni: exposure assessment and hazard characterization : growth, survival and infectivity of Campylobacter jejuni
    Verhoeff-Bakkenes, L. - \ 2012
    Wageningen University. Promotor(en): Marcel Zwietering, co-promotor(en): Rijkelt Beumer; R. de Jonge. - [S.l.] : s.n. - ISBN 9789461731241 - 144
    campylobacter jejuni - groei - overleving - infectiviteit - bacterieziekten - risicoschatting - voedselmicrobiologie - campylobacter jejuni - growth - survival - infectivity - bacterial diseases - risk assessment - food microbiology

    Campylobacter jejuni, a small, curved or spirally shaped highly motile microorganism, is identified as a major cause of bacterial gastroenteritis throughout the world. Serious complications such as the Guillain-Barré syndrome and reactive arthritis might occasionally follow infection. In this thesis data were generated in the fields of hazard characterization and exposure assessment, which were used to identify risk factors for Campylobacter.

    Although C. jejuni is generally seen as an obligate micro-aerophile, in this thesis it was shown that it can grow aerobically in the presence of pyruvate, and growth might also be possible in the presence of other antioxidants. However, as result of the strict minimal growth temperature (30ºC), C. jejuni is still assumed to be generally unable to grow in foods and therefore growth is not considered as a large risk for campylobacteriosis.

    C. jejunican, and does, survive effectively for long periods of time under non-growing conditions in various environments. Temperature is the most influencing factor in survival and survival will be optimal at low temperatures (around 4ºC). As many foods are stored chilled, this will prolong the survival of C. jejuni. Furthermore survival is enhanced at low oxygen conditions, as often present in packaged foods. While the effects of environmental conditions on the survival of C. jejuni have been studied extensively, the knowledge of the effect of environmental factors on the infectivity was scarce. Therefore, the effect of environmental conditions (temperature, medium and atmosphere) on both the survival of C. jejuni and the infectivity of the surviving cells was investigated. We revealed that culturability and infectivity are linearly related. Furthermore, our study on the effect on the infectivity of adding nonculturable C. jejuni cells to culturable cell suspensions, showed nonculturable cells not to be infective (in vitro). Therefore, absence of culturable C. jejuni cells indicates that a product can be regarded as representing a very low risk with respect to campylobacteriosis.

    Food products can be contaminated with Campylobacter during production or afterwards at the consumer’s home. Once contaminated the risk is high that Campylobacter will survive on food products until the moment of consumption, except if the product undergoes an elimination step during preparation, such as heating. The growth requirements for Campylobacter are met in the gastrointestinal tract of warm-blooded animals. As a result especially products of animal origin, like chicken meat and raw milk, are often contaminated by Campylobacter, but also products of non-animal origin, like vegetables and fruits, can be contaminated. Within the exposure assessment cross-contamination in the home, the importance of raw vegetables and fruits as a risk factor for Campylobacter, and the relative importance of chicken meat, raw milk and raw vegetables and fruits were studied.

    The effect of different cross-contamination routes during the preparation of a chicken fruit salad was investigated. It was shown that the mean transfer rate by cross-contamination was 0.12% of the initial number of C. jejunion the chicken fillet, and that the different tested cross-contamination routes; cutlery, cutting board and hands, were equally important. The high prevalence and concentration of C. jejuni on chicken meat, the high percentage of consumers who exhibit improper hygienic and cleaning behaviour, and the significant transfer of Campylobacter during improper food preparation, indicate cross-contamination from raw foods, such as chicken, to other ready-to-eat foods as a large risk factor for Campylobacter infection.

    Fresh produce can become contaminated with C. jejuni during cultivation or processing. Especially vegetables and fruits which are eaten raw may present a risk. In this thesis Dutch data on the prevalence of Campylobacter on raw vegetables and fruits were newly analysed. Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a prevalence of 0.23% (95% confidence interval (Cl): 0.12-0.39%). The prevalence on packaged products was significantly higher than on unpackaged products.

    Finally, the newly acquired data and quantitative literature data on the prevalence and concentration of Campylobacter entering the consumer phase were summarized for three food groups; vegetables and fruit, chicken, and raw milk. These data were used in a quantitative risk assessment model to estimate the exposure and the number of illnesses as result of the consumption of these foods and to compare their relative importance. The prevalence and concentration are low on raw vegetables and fruit, but the quantity of raw vegetables and fruits consumed is very high. In contrast, raw chicken and raw milk show relative high prevalence and concentration levels, but the consumption is low. Despite the differences in parameters, the exposure calculated out of the combination of parameters indicates all these three foods as high risk factors for Campylobacter. So foods which are not heavily contaminated with Campylobacter, but are consumed in large quantities can constitute a similar high risk on Campylobacter infection as foods which are consumed in small quantities but are heavily contaminated with Campylobacter.

    Darmbacteriën zijn herkenbare ecosystemen
    Vos, W.M. de - \ 2011
    Resource: weekblad voor Wageningen UR (2011). - p. 10 - 10.
    voedselmicrobiologie - microbiota van het spijsverteringskanaal - voedingsstoffen - bacteriën - voeding en gezondheid - food microbiology - gastrointestinal microbiota - nutrients - bacteria - nutrition and health
    Mensen kun je onderverdelen in drie groepen aan de hand van de bacteriesamenstelling in de darm. Deze groepen komen, net als bloedgroepen, overal ter wereld voor en zijn onafhankelijk van leeftijd, voedingspatroon of ras
    Afweer bacteriën ontrafeld
    Oost, J. van der - \ 2011
    Resource: nieuwssite voor studenten en medewerkers van Wageningen UR (2011). - ISSN 1389-7756
    voedselmicrobiologie - bacteriën - immuunsysteem - yoghurt - virussen - food microbiology - bacteria - immune system - viruses
    Bacteriën beschikken, net als planten en dieren, over diverse afweersystemen tegen virussen en andere indringers. Onderzoekers van het Wagenings Laboratorium voor Microbiologie hebben - samen met Amerikaanse en Russische collega's - de werking van één ervan vrijwel ontrafeld, zo melden zij begin juni in het wetenschappelijke tijdschrift PNAS. Dat is niet alleen van belang voor het fundamentele onderzoek naar bacteriën, maar ook handig voor fabrikanten die met bacteriën werken, zoals bijvoorbeeld in de zuivelindustrie
    Hoe effectief zijn uw voedselveiligheidssystemen? (2)
    Luning, P.A. ; Jacxsens, L. ; Kirezieva, K.K. ; Devlieghere, F. ; Uyttendaele, M. ; Boekel, T. van - \ 2011
    Voedingsmiddelentechnologie 44 (2011)1/2. - ISSN 0042-7934 - p. 16 - 19.
    voedselveiligheid - voedselhygiëne - risicoschatting - risicovermindering - bemonsteren - voedselmicrobiologie - diagnostische technieken - kwaliteitszorg - food safety - food hygiene - risk assessment - risk reduction - sampling - food microbiology - diagnostic techniques - quality management
    Binnen het Europees project PathogenCombat is het diagnose instrument ontwikkeld. Hiermee krijgt de voedingsmiddelenproducent een indruk van het risiconiveau van de context waarin zijn voedselveiligheidssysteem opereert. Daarnaast geeft het inzicht in het prestatieniveau van zowel het systeem zelf als van de microbiële output van het systeem.
    Hoe effectief zijn uw voedselveiligheidssystemen?
    Jacxsens, L. ; Luning, P.A. ; Boekel, T. van; Devlieghere, F. ; Uyttendaele, M. - \ 2010
    Voedingsmiddelentechnologie 43 (2010)25. - ISSN 0042-7934 - p. 11 - 14.
    voedselveiligheid - voedselhygiëne - voedselmicrobiologie - risicoschatting - risicovermindering - efficiëntie - bemonsteren - protocollen - procesmanagement - haccp - bedrijfsinformatiesystemen - food safety - food hygiene - food microbiology - risk assessment - risk reduction - efficiency - sampling - protocols - process management - haccp - management information systems
    Binnen het Europees project PathogenCombat zijn nieuwe tools ontwikkeld waarmee de prestaties van een voedselveiligheidssysteem kunnen worden gemeten. Vandaag deel 1 over het Microbial Assessment Scheme (MAS), een protocol voor een microbiologisch monternameplan.
    Interactie darmbacteriën en gastheer onderzoeken
    Vos, W.M. de - \ 2010
    VoedingsMagazine 23 (2010)2. - ISSN 0922-8012
    voedselmicrobiologie - lactobacillus rhamnosus - anaërobe micro-organismen - slijm - melkzuurbacteriën - darmen - microbiota van het spijsverteringskanaal - food microbiology - anaerobes - mucus - lactic acid bacteria - intestines - gastrointestinal microbiota
    Begin dit jaar honoreerde de European Research Council een onderzoeksvoorstel van prof. Willem de Vos. De subsidie maakt onderzoek mogelijk naar activiteiten in de darm van Lactobacillus rhamnosus GG en Akkermansia muciniphila, twee micro-organismen die interacties hebben met mucus in de darm. ‘De klinische consequenties kunnen van groot belang zijn.’ De wetenschappelijke onderzoeksorganisatie ERC van de Europese Unie heeft een Advanced Investigator Grant toegekend aan prof. Willem de Vos, hoogleraar microbiologie bij Wageningen Universiteit en Finland Distinguished Professor in een programma van de Finse Academie van Wetenschap en TEKES. De beurs, een onderzoekssubsidie van € 2,5 miljoen, is een erkenning van ‘zijn kwaliteiten als Europees onderzoeksleider in combinatie met zijn voorstel voor baanbrekend onderzoek’, aldus de ERC. Willem de Vos is bijzonder ingenomen met de toekenning: ‘Ik zie het als een onderscheiding, uiteraard niet alleen voor mijzelf, maar ook voor mijn medewerkers. De Wageningse leerstoelgroep Microbiologie is de laatste jaren sterk gegroeid. We hebben twee leerstoelen, twee persoonlijke hoogleraren en een buitengewoon hoogleraar, en een tiental UHDs en UDs. Daarnaast zijn er postdocs, technisch medewerkers en ongeveer 50 aio’s. Voor het nu goedgekeurde projectvoorstel Exploitation of Intestinal Microbes gaan we tijdelijk nog vijf postdocs en aio’s aantrekken.’
    Microbiologische voedselveiligheid
    Beumer, R.R. - \ 2010
    In: 76 Voeding en Diëtetiek, Voedingsleer Houten : Bohn Stafleu van Loghum - p. 1 - 26.
    voedselveiligheid - voedselmicrobiologie - voedselinspectie - infecties - voedselvergiftiging - voedselbesmetting - voeding en gezondheid - voedselbederf - food safety - food microbiology - food inspection - infections - food poisoning - food contamination - nutrition and health - food spoilage
    Ondanks veel maatregelen op het gebied van hygiëne lukt het nog steeds niet om het aantal geregistreerde voedselinfecties drastisch te verminderen. Integendeel, het lijkt er zelfs op dat de incidentie toeneemt. Verschillende factoren spelen hierbij een rol: onvoldoende kennis bij producenten, bereiders en consumenten van levensmiddelen, en veranderingen in de commerciële voedselproductie (meer kant en klaar maaltijden die minimaal geconserveerd worden). Maar het kan ook (deels) veroorzaakt worden door een terugtrekkende overheid, bijvoorbeeld de Voedsel en Warenautoriteit die steeds meer taken overlaat aan de particuliere sector. Om het aantal voedselinfecties zoveel mogelijk terug te dringen moet er aan drie voorwaarden worden voldaan: 1) besmetting zoveel mogelijk voorkomen, 2) uitgroei van micro-organismen remmen, en 3) de consument, zo jong mogelijk, voldoende relevante kennis bijbrengen op dit gebied. Wordt aan al deze voorwaarden voldaan, dan zal het aantal voedselinfecties kunnen dalen. Men moet zich goed beseffen dat deze nooit geheel zullen verdwijnen.
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