| 1. |
- Boqvist, Sofia, et al.
(author)
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Prevalence of Verotoxigenic Escherichia coli O157:H7 in Fecal and Ear Samples from Slaughtered Cattle in Sweden
- 2009
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In: Journal of Food Protection. - 0362-028X. ; 72, s. 1709-1712
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Journal article (peer-reviewed)abstract
- A national verotoxigenic Escherichia coli (VTEC) O157:H7 monitoring study was carried out among cattle at slaughter in Sweden during 2005 and 2006. Sixty (3.4%; 95% confidence interval, 3.3 to 3.5%) of 1,758 fecal samples collected and 54 (12% 95% confidence interval, 11.9 to 12.4 %) of 446 ear samples tested positive for VTEC O157:H7. Ear samples were included to evaluate whether they could be used to assess general VTEC O157:H7 contamination at slaughter. The respective prevalences of positive fecal and ear samples were 16 and 21% for older calves, 3.5 and 10% for young stock, and 1.6 and 12% for adult cattle. There were significant differences between the age groups for the fecal samples, but not for the ear samples. It could be that ear samples are less subject to age variations due to environmental factors, or perhaps this observation was due to fewer ear samples being collected in this study. Within the age groups, the prevalence of VTEC O157:H7-positive ear samples was significantly higher than that of fecal samples for young stock and adult cattle. Furthermore, the prevalence of positive ear samples fluctuated more widely throughout the year than that of positive fecal samples. The fecal prevalence data can be used as baseline data against which future intervention strategies can be evaluated, and the ear samples can be used as an indicator of environmental contamination. The results of the ear samples are too limited to determine if they can be used to detect hide contamination and risk of carcass contamination.
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| 2. |
- Johansson, Monika, et al.
(author)
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Casein Breakdown in Bovine Milk by a Field Strain of Staphylococcus aureus
- 2013
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In: Journal of Food Protection. - 0362-028X. ; 76, s. 1638-1642
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Journal article (peer-reviewed)abstract
- The objectives of this study were to establish the proteolytic effects of Staphylococcus aureus during mastitis on economically important milk proteins. Concentrations of milk proteins were determined by capillary electrophoresis in an experimental model using a field strain of S. aureus. The pathogen was inoculated into bacteria-free control milk to imitate proteolysis caused by the pathogen in the mammary gland between milkings. Milk content of caseins (CN) alpha(S1), alpha(S2), kappa, beta(A1), and beta(A2) and whey proteins alpha-lactalbumin and beta-lactoglobulin were analyzed initially and after 6 h of incubation. After 6 h, the overall CN content was significantly reduced (21%) in milk inoculated with S. aureus compared with the bacteria-free control milk. S. aureus significantly lowered concentration of alpha(S1)-CN (2.5%), beta(A1)-CN (3%), and beta(A2)-CN (5%). S. aureus also hydrolyzed kappa-CN into para-kappa-CN, with significant reduction of kappa-CN (7.4%) as a consequence.
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| 3. |
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| 4. |
- Maes, Sharon, 1990-, et al.
(author)
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Evaluation of Two Surface Sampling Methods for Microbiological and Chemical Analyses To Assess the Presence of Biofilms in Food Companies
- 2017
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In: Journal of Food Protection. - : Elsevier BV. - 0362-028X .- 1944-9097. ; 80:12, s. 2022-2028
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Journal article (peer-reviewed)abstract
- Biofilms are an important source of contamination in food companies, yet the composition of biofilms in practice is stillmostly unknown. The chemical and microbiological characterization of surface samples taken after cleaning and disinfection isvery important to distinguish free-living bacteria from the attached bacteria in biofilms. In this study, sampling methods that arepotentially useful for both chemical and microbiological analyses of surface samples were evaluated. In the manufacturingfacilities of eight Belgian food companies, surfaces were sampled after cleaning and disinfection using two sampling methods:the scraper–flocked swab method and the sponge stick method. Microbiological and chemical analyses were performed on thesesamples to evaluate the suitability of the sampling methods for the quantification of extracellular polymeric substancecomponents and microorganisms originating from biofilms in these facilities. The scraper–flocked swab method was mostsuitable for chemical analyses of the samples because the material in these swabs did not interfere with determination of thechemical components. For microbiological enumerations, the sponge stick method was slightly but not significantly moreeffective than the scraper–flocked swab method. In all but one of the facilities, at least 20% of the sampled surfaces had more than102 CFU/100 cm2. Proteins were found in 20% of the chemically analyzed surface samples, and carbohydrates and uronic acidswere found in 15 and 8% of the samples, respectively. When chemical and microbiological results were combined, 17% of thesampled surfaces were contaminated with both microorganisms and at least one of the analyzed chemical components; thus, thesesurfaces were characterized as carrying biofilm. Overall, microbiological contamination in the food industry is highly variable byfood sector and even within a facility at various sampling points and sampling times.
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| 5. |
- Maes, Sharon, 1990-, et al.
(author)
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Identification and Spoilage Potential of the Remaining Dominant Microbiota on Food Contact Surfaces after Cleaning and Disinfection in Different Food Industries
- 2019
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In: Journal of Food Protection. - : Elsevier BV. - 0362-028X .- 1944-9097. ; 82:2, s. 262-275
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Journal article (peer-reviewed)abstract
- After cleaning and disinfection (C&D), surface contamination can still be present in the production environment of foodcompanies. Microbiological contamination on cleaned surfaces can be transferred to the manufactured food and consequentlylead to foodborne illness and early food spoilage. However, knowledge about the microbiological composition of residualcontamination after C&D and the effect of this contamination on food spoilage is lacking in various food sectors. In this study,we identified the remaining dominant microbiota on food contact surfaces after C&D in seven food companies and assessed thespoilage potential of the microbiota under laboratory conditions. The dominant microbiota on surfaces contaminated at 102CFU/100 cm2 after C&D was identified based on 16S rRNA sequences. The ability of these microorganisms to hydrolyzeproteins, lipids, and phospholipids, ferment glucose and lactose, produce hydrogen sulfide, and degrade starch and gelatin alsowas evaluated. Genera that were most abundant among the dominant microbiota on food contact surfaces after C&D werePseudomonas, Microbacterium, Stenotrophomonas, Staphylococcus, and Streptococcus. Pseudomonas spp. were identified infive of the participating food companies, and 86.8% of the isolates evaluated had spoilage potential in the laboratory tests.Microbacterium and Stenotrophomonas spp. were identified in five and six of the food companies, respectively, and all testedisolates had spoilage potential. This information will be useful for food companies in their quest to characterize surfacecontamination after C&D, to identify causes of microbiological food contamination and spoilage, and to determine the need formore thorough C&D.
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| 6. |
- Mphande, FA, et al.
(author)
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Fungi, aflatoxins, and cyclopiazonic acid associated with peanut retailing in Botswana
- 2004
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In: Journal of food protection. - : International Association for Food Protection. - 0362-028X .- 1944-9097. ; 67:1, s. 96-102
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Journal article (peer-reviewed)abstract
- Peanuts are important food commodities, but they are susceptible to fungal infestation and mycotoxin contamination. Raw peanuts were purchased from retail outlets in Botswana and examined for fungi and mycotoxin (aflatoxins and cyclopiazonic acid) contamination. Zygomycetes were the most common fungi isolated; they accounted for 41% of all the isolates and were found on 98% of the peanut samples. Among the Zygomycetes, Absidia corymbifera and Rhizopus stolonifer were the most common. Aspergillus spp. accounted for 35% of all the isolates, with Aspergillus niger being the most prevalent (20.4%). Aspergillus flavus/parasiticus were also present and accounted for 8.5% of all the isolates, with A. flavus accounting for the majority of the A. flavus/parasiticus identified. Of the 32 isolates of A. flavus screened for mycotoxin production, 11 did not produce detectable aflatoxins, 8 produced only aflatoxins B1 and B2, and 13 produced all four aflatoxins (B1, B2, G1, and G2) in varying amounts. Only 6 of the A. flavus isolates produced cyclopiazonic acid at concentrations ranging from 1 to 55 μg/kg. The one A. parasiticus isolate screened also produced all the four aflatoxins (1,200 μg/kg) but did not produce cyclopiazonic acid. When the raw peanut samples (n = 120) were analyzed for total aflatoxins, 78% contained aflatoxins at concentrations ranging from 12 to 329 μg/kg. Many of the samples (49%) contained total aflatoxins at concentrations above the 20 μg/kg limit set by the World Health Organization. Only 21% (n = 83) of the samples contained cyclopiazonic acid with concentrations ranging from 1 to 10 μg/kg. The results show that mycotoxins and toxigenic fungi are common contaminants of peanuts sold at retail in Botswana.
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| 7. |
- Söderqvist, Karin, et al.
(author)
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Fate of Listeria monocytogenes, Pathogenic Yersinia enterocolitica, and Escherichia coli O157:H7 gfpþ in Ready-to-Eat Salad during Cold Storage: What Is the Risk to Consumers?
- 2017
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In: Journal of Food Protection. - 0362-028X. ; 80, s. 204-212
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Journal article (peer-reviewed)abstract
- In this study, we investigated the fate of Listeria monocytogenes, pathogenic Yersinia enterocolitica, and Escherichia coli O157:H7 gfp(+) inoculated in low numbers into ready-to-eat baby spinach and mixed-ingredient salad (baby spinach with chicken meat). Samples were stored at recommended maximum refrigerator temperature (8 degrees C in Sweden) or at an abuse temperature (15 degrees C) for up to 7 days. Mixed-ingredient salad supported considerable growth when stored at 15 degrees C during shelf life (3 days), with populations of L. monocytogenes, pathogenic Y. enterocolitica, and E. coli O157:H7 gfp(+) increasing from less than 2.0 log CFU/g on day 0 to 7.0, 4.0, and 5.6 log CFU/g, respectively. However, when mixed-ingredient salad was stored at 8 degrees C during shelf life, only L. monocytogenes increased significantly, reaching 3.0 log CFU/g within 3 days. In plain baby spinach, only pathogenic Y. enterocolitica populations increased significantly during storage for 7 days, and this was exclusively at an abuse temperature (15 degrees C). Thus, mixing ready-to-eat leafy vegetables with chicken meat strongly influenced levels of inoculated strains during storage. To explore the food safety implications of these findings, bacterial numbers were translated into risks of infection by modeling. The risk of listeriosis (measured as probability of infection) was 16 times higher when consuming a mixed ingredient salad stored at 8 degrees C at the end of shelf life, or 200,000 times higher when stored at 15 degrees C, compared with when consuming it on the day of inoculation. This indicates that efforts should focus on preventing temperature abuse during storage to mitigate the risk of listeriosis. The storage conditions recommended for mixed-ingredient salads in Sweden (maximum 8 degrees C for 3 days) did not prevent growth of L. monocytogenes in baby spinach mixed with chicken meat. Manufacturers preparing these salads should be aware of this, and recommended storage temperature should be revised downwards to reduce the risk of foodborne disease.
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| 8. |
- Söderqvist, Karin, et al.
(author)
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Foodborne Bacterial Pathogens in Retail Prepacked Ready-to-Eat Mixed Ingredient Salads
- 2016
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In: Journal of Food Protection. - 0362-028X. ; 79, s. 978–985-
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Journal article (peer-reviewed)abstract
- Pre-packed ready-to-eat mixed ingredient salads (RTE salads) are readily available whole meals that include a variety of ingredients such as raw vegetables, cooked meat, and pasta. As part of a trend toward healthy convenience foods, RTE salads have become an increasingly popular product among consumers. However, data on the incidence of foodborne pathogens in RTE salads are scarce. In this study, the microbiological safety of 141 RTE salads containing chicken, ham, or smoked salmon was investigated. Salad samples were collected at retail and analyzed using standard methods for Listeria monocytogenes, Shiga toxin-producing Escherichia coli (STEC), pathogenic Yersinia enterocolitica, Salmonella, and Campylobacter spp. L. monocytogenes was isolated from two (1.4%) of the RTE salad samples. Seven (5.0%) of the samples were positive for the ail-gene (present in all human pathogenic Y. enterocolitica) and three (2.1%) of the samples were positive for the Shiga toxin-genes stx1 and/or stx2. However, no strains of pathogenic Y. enterocolitica or STEC were isolated. Thus, pathogens were found or suspected in almost 1 of 10 RTE salads investigated, and pathogenic bacteria probably are present in various RTE salads from retail premises in Sweden. Because RTE salads are intended to be consumed without heat treatment, control of the ingredients and production hygiene is essential to maintain consumer safety. The recommended maximum storage temperature for RTE salads varies among countries but can be up to 8 °C (e.g., in Sweden). Even during a short shelf life (3 to 5 days), storage at 8 °C can enable growth of psychrotrophs such as L. monocytogenes and Y. enterocolitica. The maximum storage temperature should therefore be reduced.
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| 9. |
- Söderqvist, Karin, et al.
(author)
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Season and Species: Two Possible Hurdles for Reducing the Food Safety Risk of Escherichia coli O157 Contamination of Leafy Vegetables
- 2019
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In: Journal of Food Protection. - 0362-028X. ; 82, s. 247-255
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Journal article (peer-reviewed)abstract
- The food safety risk of Shiga toxin-producing Escherichia coli (STEC) infection per serving of leafy vegetables was investigated using a quantitative microbial risk assessment (QMRA) approach. The estimated level of E. coli O157 contamination was based on observed numbers of Enterobacteriaceae and E. coli on leafy vegetables grown and processed in southern Sweden from 2014 to 2016. Samples were collected before harvest, after washing, and at the end of shelf life. The observed counts were combined with data on the ratio of E. coli to E. coli O157 taken from earlier studies to estimate the probability of illness. The risks of STEC infection associated with species, either spinach (Spinacia oleracea) or rocket (Diplotaxis tenuifolia), growing season (spring or autumn), and washing (washed or not washed) were then evaluated. The results indicated that leafy vegetable species and growing season could be possible hurdles for reducing the food safety risk of STEC infection. At harvest, the probability of infection was 87% lower when consuming rocket compared with spinach and 90% lower when consuming leafy vegetables grown in spring compared with autumn. These relative risk reductions remained consistent even with other serving sizes and dose-response models. The lowest risk of STEC infection was associated with leafy vegetables early in the production chain, i.e., before harvest, while the risk increased during storage and processing. Consequently, the highest risk was observed when leafy vegetables were consumed at the end of shelf life. Washing had no effect on the food safety risk of STEC infection in this study. To improve the quality of QMRA, there is a need for additional data on the relationship between indicator organisms that can be easily enumerated (e.g., E. coli and Enterobacteriaceae) and E. coli strains that can cause STEC infection (e.g., E. coli O157) but are difficult to identify in food samples such as leafy vegetables.
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| 10. |
- Søndergaard, M. S. R., et al.
(author)
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Low-cost monitoring of Campylobacter in poultry houses by air sampling and quantitative PCR
- 2014
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In: Journal of Food Protection. - 0362-028X .- 1944-9097. ; 77:2, s. 325-330
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Journal article (peer-reviewed)abstract
- The present study describes the evaluation of a method for the quantification of Campylobacter by air sampling in poultry houses. Sampling was carried out in conventional chicken houses in Poland, in addition to a preliminary sampling in Denmark. Each measurement consisted of three air samples, two standard boot swab fecal samples, and one airborne particle count. Sampling was conducted over an 8-week period in three flocks, assessing the presence and levels of Campylobacter in boot swabs and air samples using quantitative real-time PCR. The detection limit for air sampling was approximately 100 Campylobacter cell equivalents (CCE)/m3. Airborne particle counts were used to analyze the size distribution of airborne particles (0.3 to 10 mm) in the chicken houses in relation to the level of airborne Campylobacter. No correlation was found. Using air sampling, Campylobacter was detected in the flocks right away, while boot swab samples were positive after 2 weeks. All samples collected were positive for Campylobacter from week 2 through the rest of the rearing period for both sampling techniques, although levels 1- to 2-log CCE higher were found with air sampling. At week 8, the levels were approximately 104 and 105 CCE per sample for boot swabs and air, respectively. In conclusion, using air samples combined with quantitative realtime PCR, Campylobacter contamination could be detected earlier than by boot swabs and was found to be a more convenient technique for monitoring and/or to obtain enumeration data useful for quantitative risk assessment of Campylobacter. © International Association for Food Protection.
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