| 1. |
- Arinder, Pernilla, et al.
(författare)
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Transfer and Decontamination of S. aureus in Transmission Routes Regarding Hands and Contact Surfaces
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Hand hygiene, cleaning and disinfection are pre-requirements for hygiene management in hospital settings and the food industry. In order to facilitate risk management, different contamination scenarios and interventions need to be evaluated. In the present study data on transfer rates and reductions of Staphylococcus aureus were provided in an experimental set-up using artificial skin. Using this methodology, test persons were not exposed with pathogenic bacteria. An exposure assessment model was developed and applied to evaluate different contamination routes and hygiene interventions. The transfer rates of S. aureus from inoculated VITRO-SKIN® to fomites were calculated from blotting series. The VITRO-SKIN® was more prone to spread bacteria than fomites. When different surfaces were cleaned, the reduction of S. aureus varied between <1 and 7 log CFU. It could not be concluded that a certain coupon material, cleaning agent, cleaning wipe, soiling or humidity consistently resulted in a high or low reduction of S. aureus. The reduction of S. aureus and E. coli during hand washing was evaluated on artificial skin, VITRO-SKIN®. The reduction of E. coli on VITRO-SKIN® was similar to the log reduction obtained when washing human hands. The S. aureus count on a human hand was both calculated in different scenarios describing different contamination routes starting from a contaminated hand using the exposure assessment model, and measured on an experimental setup using VITRO-SKIN® for validation. A linear relationship was obtained between the analysed level of S. aureus and the calculated level. However, the calculated levels of S. aureus on the VITRO-SKIN® in the scenarios were 1–1.5 log lower than the analysed level. One of the scenarios was used to study the effect of interventions like hand washing and cleaning of surfaces.
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| 2. |
- Aronsson, Kristina, et al.
(författare)
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Growth of pulsed electric field exposed Escherichia coli in relation to inactivation and environmental factors
- 2004
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Ingår i: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 93:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed electric fields (PEF) have been proven to inactivate microorganisms during nonthermal conditions and have the potential to replace thermal processing as a method for food preservation. However, there is a need to understand the recovery and growth of survivors and potentially injured microorganisms following PEF processing. The purpose of this investigation was to study the growth of Escherichia coli at 10°C following exposure to electrical field strengths (15, 22.5 and 30 kV/cm) in relation to inactivation and the amount of potentially sublethally injured cells. One medium was used as both a treatment medium and an incubation medium, to study the influence of environmental factors on the inactivation and the growth of the surviving population. The pH (5.0, 6.0 and 7.0) and water activity (1.00, 0.985 and 0.97) of the medium was varied by adding HCl and glycerol, respectively. Growth was followed continuously by measuring the optical density. The time-to-detection (td) and the maximum specific growth rate (?max) were calculated from these data. Results showed that the PEF process did not cause any obvious sublethal injury to the E. coli cells. The number of survivors was a consequence of the combination of electrical field strength and environmental factors, with pH being the most prominent. Interestingly, the ?max of subsequent growth was influenced by the applied electrical field strength during the process, with an increased ?max at more intense electrical field strengths. In addition, the ?max was also influenced by the pH and water activity. The td, which could theoretically be considered as an increase in shelf life, was found to depend on a complex correlation between electrical field strength, pH and water activity. That could be explained by the fact that the td is a combination of the number of survivors, the recovery of sublethal injured cells and the growth rate of the survivors. © 2003 Published by Elsevier B.V.
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| 3. |
- Aronsson, Kristina, et al.
(författare)
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Inactivation of Escherichia coli, Listeria innocua and Saccharomyces cerevisiae in relation to membrane permeabilization and subsequent leakage of intracellular compounds due to pulsed electric field processing
- 2005
-
Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 99:1, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- Membrane permeabilization, caused by pulsed electric field (PEF) processing of microbial cells, was investigated by measurement of propidium iodide (PI) uptake with flow cytometry. Inactivation of Escherichia coli, Listeria innocua and Saccharomyces cerevisiae was determined by viable counts, and leakage of intracellular compounds, such as ATP and UV-absorbing substances, was measured in the extracellular environment. Electrical field strength and pulse duration influenced membrane permeabilization of all three tested organisms of which S. cerevisiae was the most PEF sensitive, followed by E. coli and L. innocua. It was shown by viable counts, PI uptake and leakage of intracellular compounds that L. innocua was the most resistant. Increased inactivation corresponded to greater numbers of permeabilized cells, which were reflected by increased PI uptake and larger amounts of intracellular compounds leaking from cells. For E. coli and L. innocua, a linear relationship was observed between the number of inactivated cells (determined as CFU) and cells with permeated membranes (determined by PI uptake), with higher number of inactivated cells than permeated cells. Increased leakage of intracellular compounds with increasing treatment severity provided further evidence that cells were permeabilized. For S. cerevisiae, there was higher PI uptake after PEF treatments, although very little or no inactivation was observed. Results suggest that E. coli and L. innocua cells, which took up PI, lost their ability to multiply, whereas cells of S. cerevisiae, which also took up PI, were not necessarily lethally permeabilized. © 2004 Elsevier B.V. All rights reserved.
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| 4. |
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| 5. |
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| 6. |
- Blixt, Y., et al.
(författare)
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Interlaboratory random amplified polymorphic DNA typing of Yersinia enterocolitica and Y. enterocolitica-like bacteria
- 2003
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Ingår i: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 83:1, s. 15-26
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Tidskriftsartikel (refereegranskat)abstract
- A random amplified polymorphic DNA (RAPD) protocol was developed for interlaboratory use to discriminate food-borne Yersinia enterocolitica O:3 from other serogroups of Y. enterocolitica and from Y. enterocolitica-like species. Factors that were studied regarding the RAPD performance were choice of primers and concentration of PCR reagents (template DNA, MgCl 2, primer and Taq DNA polymerase). A factorial design experiment was performed to identify the optimal concentrations of the PCR reagents. The experiment showed that the concentration of the PCR reagents tested significantly affected the number of distinct RAPD products. The RAPD protocol developed was evaluated regarding its discrimination ability using 70 different Yersinia strains. Cluster analysis of the RAPD patterns obtained revealed three main groups representing (i) Y. pseudotuberculosis, (ii) Y. enterocolitica and (iii) Y. kristensenii, Y. frederiksenii, Y. intermedia and Y. ruckeri. Within the Y. enterocolitica group, the European serovar (O:3) and the North American serovar (O:8) could be clearly separated from each other. All Y. enterocolitica O:3 strains were found in one cluster which could be further divided into two subclusters, representing the geographical origin of the isolates. Thus, one of the subclusters contained Y. enterocolitica O:3 strains originating from Sweden, Finland and Norway, while Danish and English O:3 strains were found in another subcluster together with O:9 and O:5,27 strains. The repeatability (intralaboratory) and reproducibility (interlaboratory) of the RAPD protocol were tested using 15 Yersinia strains representing different RAPD patterns. The intralaboratory and the interlaboratory studies gave similarity coefficients of the same magnitude (generally >70%) for the individual strains. In the present study, it was shown that interreproducible RAPD results could be achieved by appropriate optimisation of the RAPD protocol. Furthermore, the study reflects the heterogeneous genetic diversity of the Y. enterocolitica species. © 2002 Elsevier Science B.V. All rights reserved.
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| 7. |
- Borch, Elisabeth, et al.
(författare)
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Bacteriological safety issues in red meat and ready-to-eat meat products, as well as control measures
- 2002
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Ingår i: Meat Science. - 0309-1740 .- 1873-4138. ; 62:3, s. 381-390
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Tidskriftsartikel (refereegranskat)abstract
- The importance of Eschericha coli O157, Listeria monocytogenes and Salmonella typhimurium DT104 as meat-borne pathogens is well established. Pathogenic bacteria such as Aeromonas spp., Arcobacter spp., psychrotrophic Bacillus cereus, Campylobacter spp., Clostridium botulinum and non-invasive Listeria monocytogenes can be regarded as rookies, but not yet firmly associated with today's production of red meat and meat products. The development of PCR and other DNA-based techniques will shed new light on so called emerging pathogens. Important safety issues in meat production, such as insufficient cleaning and disinfection (including the stable/lairage, processing environment), carcass decontamination and chilling, and cross contamination are discussed. Furthermore, probability modelling of survival and growth is identified as an important way to achieve a better understanding of how to deal with the complexity of further processing, including heat treatment and storage. © 2002 Elsevier Science Ltd. All rights reserved.
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| 8. |
- Borch, Elisabeth
(författare)
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Green Cleaning - Utveckling av testbädden Cleaning Innovation
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En ökad användning av miljösmart teknik och förfarande vid rengöring och desinfektion i livsmedelsindustrin förväntas leda till mindre miljöpåverkan genom mindre vatten-, energi-, kemikalie- och materialförbrukning och mindre matsvinn. Detta gynnar också tillväxten hos miljöteknikföretag som bidrar med gröna lösningar. Testbädden Cleaning Innovation (www.cleaninginnovation.se) medverkar till utveckling av miljösmarta och effektiva metoder för rengöring och desinfektion i många branscher. Huvudintressenter är leverantörer/utvecklare av kemikalier, utrustning eller material; hygienföretag; livsmedelsföretag; offentliga aktörer. Cleaning Innovation, som ägs av RISE, är en öppen, oberoende testbädd och erbjuder utvärdering av teknik, kemikalier, material, utrustning och metoder. Testbädden bygger på samverkan mellan olika typer av verksamheter inom RISE (Research Institutes of Sweden) inriktade mot mikrobiologi, miljö, processteknik, certifiering, mätteknik, kemi, material, energiteknik samt med hygienteknikföretaget Lagafors AB. Inom Cleaning Innovation finns marknadskunskap, tvärvetenskaplig kompetens, analys-, beräknings- och mätutrustning, laboratorier samt testutrustningar i pilotskala. I projektet utvecklades befintlig verksamhet avseende testlokal, utrustning och produkterbjudande. Ett viktigt resultat från projektet är att vi har genomfört mer än 10 projekt där utvärdering av renhet och desinfektion görs med kunder. Eftersom detta är betydligt mer än planerat har egen finansiering blev betydligt högre än budgeterad. Detta visar på ett bra utbud och en tydlig marknad. Vi har också breddat vår målgrupp och inkluderar nu alla branscher med behov av rengöring och desinfektion; i motsats till bara livsmedelsindustrin som beskrivit i projektansökan.Testbädden Cleaning Innovation lanserades 29 november 2016. Cleaning Innovations utveckling i framtiden ser ljus ut och har en stark och naturlig förankring inom RISE. Framtidsplanerna involverar ett succesivt bräddande till kunder inom fler industrityper och en långsam expansion av verksamheten.
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| 9. |
- Borch, Elisabeth, et al.
(författare)
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Influence of long-chain polyphosphate and heat treatment on Clostridium cochlearium and Clostridium sporogenes isolated from processed cheese spread
- 2007
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Ingår i: Journal of Food Protection. - 0362-028X .- 1944-9097. ; 70:3, s. 744-747
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Tidskriftsartikel (refereegranskat)abstract
- The outgrowth of Clostridium spp. spores causes spoilage in processed cheese products due to gas and off-odor formation. The present study focuses on the response of spores of Clostridium sporogenes and Clostridium cochlearium at 25°C to polyphosphate, both alone and in combination with heat treatment. The two strains used were isolated from spoiled cheese spread. The addition of 1.5% polyphosphate but not 0.75% polyphosphate totally inhibited the growth of C. sporogenes SIK4.3; in contrast, 0.75% polyphosphate was sufficient to totally inhibit C. cochlearium CCUG 45978. The highest polyphosphate concentration tested (1.5%) was sporicidal for C. sporogenes SIK4.3 but not for C. cochlearium CCUG 45978. When 0.75% polyphosphate Bekaplus FS was combined with a holding time of 5 min at 98°C, no survival or growth of C. sporogenes SIK4.3 was detected; however, the same effect was not achieved through heating alone or through application of polyphosphate alone. C. cochlearium CCUG 45978 was more heat tolerant, as shown by higher D-values. In conclusion, the results strongly suggest that polyphosphate Bekaplus FS has the potential to restrict the growth of C. sporogenes and C. cochlearium in cheese spread stored at ambient storage temperature. Experiments with cheese are needed in order to verify this effect. Copyright ©, International Association for Food Protection.
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| 10. |
- Dahlenborg, Maria, et al.
(författare)
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Prevalence of Clostridium botulinum types B, E, and F in faecal samples from Swedish cattle.
- 2003
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Ingår i: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 82:2, s. 105-110
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Tidskriftsartikel (refereegranskat)abstract
- Faeces were collected from 60 cows at three slaughterhouses situated in southern and central Sweden. The faecal samples were collected during two sampling periods over the year, summer and winter. All samples were analysed for the presence of Clostridium botulinum spores, according to a combined selection and enrichment PCR procedure. One PCR assay was specific for part of the type B neurotoxin gene, while the other assay was specific for both type E and F neurotoxin genes. The prevalence of C. botulinum in Swedish cattle was established to be 73% for non-proteolytic type B and less than 5% for types E and F. Twenty-eight (64%) of the positive faecal samples had a spore load of less than 4 spores/g. Statistical analysis (ANOVA) showed that seasonal variation (summer and winter) had a significant effect on the prevalence of C. botulinum type B in cattle, whereas the effect of geographical location of rearing of the cattle (southern and central Sweden) was less significant.
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| 11. |
- Eriksson, E., et al.
(författare)
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Verocytotoxin-producing Escherichia coli 0157:H7 in the Swedish pig population
- 2003
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Ingår i: The Veterinary Record. - 0042-4900 .- 2042-7670. ; 152:23, s. 712-717
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Tidskriftsartikel (refereegranskat)abstract
- Verocytotoxin-producing Escherichia coli O157:H7 (VTEC O157:H7) was detected in two of 2446 individual faecal samples collected from pigs slaughtered at five Swedish slaughterhouses, indicating a prevalence of 0.08 per cent, with a 95 per cent confidence interval from 0 to 0-16 per cent. Four Swedish VTEC O157:H7-positive farms which kept ruminants and pigs were studied by repeated faecal sampling; VTEC O157:H7 was isolated from the ruminants and pigs on all the farms and the same strains were present in the pigs and the ruminants. On one of the farms, the organism persisted in the pig population for 11 months. On all four farms, management practices which might have influenced the isolation rate in pigs were identified. A group of young VTEC O157:H7-positive pigs was moved from one of the VTEC O157:H7-positive farms to a fattening herd where there were no ruminants. The number of VTEC O157:H7-positive faecal samples decreased gradually and after nine weeks the pigs were all negative; at slaughter none of the pigs was VTEC O157:H7-positive.
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| 12. |
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| 13. |
- Knutsson, Rickard, et al.
(författare)
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Evaluation of selective enrichment PCR procedures for Yersinia enterocolitica.
- 2002
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Ingår i: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 73:1, s. 35-46
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Tidskriftsartikel (refereegranskat)abstract
- Four enrichment PCR protocols for detecting unlysed cells of pathogenic Yersinia enterocolitica were studied. First, the probability of detecting Y. enterocolitica cells of known concentrations by a multiplex PCR assay was determined, and it was found to follow a logistic regression model. From this model, the probability of detecting Y enterocolitica at a specific concentration could be estimated; for example, the detection probability of 10(4) CFU/ml was estimated to be 85.4%. The protocols were evaluated on enrichment cultures inoculated with 10(2) CFU/ml Y. enterocolitica and 10(2)-10(6) CFU/ml of a defined background flora. For each protocol, the time for sample withdrawal and the presence of background flora were studied with respect to PCR detection. The optimal point in time of sample withdrawal was found to be different for each protocol employed. Early detection was favoured by concentrating the target cells, and the most rapid PCR detection of Y. enterocolitica was achieved with enrichment in Yersinia-PCR-compatible-enrichment (YPCE) medium for 3 h at 25 degrees C, followed by a centrifugation prior to PCR analysis. For detection of Y. enterocolitica in the presence of high concentrations (10(6) CFU/ml) of background flora, a long incubation time followed by density centrifugation and a dilution step was most successful. The protocol that gave the most reliable PCR detection in the presence of 10(6) CFU/ml background flora included 24 h incubation in Yersinia-selective-enrichment (YSE) broth at 25 degrees C, followed by Percoll density centrifugation, and a 100 times dilution prior to PCR analysis.
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| 14. |
- Kure, C.F., et al.
(författare)
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Use of the selective agar medium CREAD for monitoring the level of airborne spoilage moulds in cheese production
- 2008
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 122:42006, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- It was investigated if a selective medium for common cheese spoiling moulds (CREAD) could give more relevant information than a general mould medium in hygienic air-sampling in cheese factories. A total of 126 air-samples were taken in six Nordic cheese factories using the general mould medium DG18 and CREAD. The level and genera of air-borne mould was determined. Identification to species-level was performed for a selection of samples. In five cheese factories the mycobiota was dominated by Penicillium spp. and in one cheese factory by Cladosporium spp. The concentration of air-borne moulds varied between the cheese factories ranging from 1 to 270 cfu/m3 on DG18 with a median value of 17. The number of mould colonies was in general lower at CREAD. Identification indicated that CREAD supported growth of common spoilage moulds for cheese, such as Penicillium palitans and P. commune. The mycobiota on DG18 also consisted of moulds not commonly associated with spoilage of cheese, such as Cladosporium spp., P. brevicompactum and P. chrysogenum. Contamination of cheese with mould is periodically a problem in production of semi-hard cheese and the level of air-borne mould is therefore routinely monitored in cheese factories. A clear correlation between the total number of moulds in air and mould growth on products is not always found. The conclusion from the investigation is that it is recommended to use a selective medium for cheese spoilage moulds, such as CREAD in hygienic monitoring. © 2007 Elsevier B.V. All rights reserved.
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| 15. |
- Li, Shengjie, et al.
(författare)
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Inter-relationships between the metrics of instrumental meat color and microbial growth during aerobic storage of beef at 4°C
- 2015
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Ingår i: Acta agriculturae Scandinavica. Section A, Animal science. - : Informa UK Limited. - 0906-4702 .- 1651-1972. ; 65:2, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate the inter-relationships between changes in beef color and microbial growth when steaks from longissimus thoracis et lumborum muscles were overwrapped with polyvinyl chloride film and stored at 4°C. At day 0, 4, 7 and 10 instrumental color (CIE L*, a*, b* and spectral scans) and microbial counts were measured. Bacterial communities were characterized through Terminal Restriction Fragment Length Polymorphism analysis. Both meat discoloration and microbial spoilage occurred at day 10. Total viable count, Enterobacteriaceae count and the relative abundance of Pseudomonas spp. and Acinetobacter spp. were significantly correlated with color metrics associated with discoloration. These findings indicate that meat discoloration and microbial growth may not be totally independent effects and changes in a*, Chroma and hue angle may be an indicator of meat spoilage under this specific storage condition. Meanwhile, Enterobacteriaceae and aerobic bacteria might play important roles in meat discoloration.
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| 16. |
- Lycken, L., et al.
(författare)
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Characterization of Clostridium spp. isolated from spoiled processed cheese products
- 2006
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Ingår i: Journal of Food Protection. - 0362-028X .- 1944-9097. ; 69:8, s. 1887-1891
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Tidskriftsartikel (refereegranskat)abstract
- Of 42 spoiled cheese spread products, 35 were Found to harbor Clostridium spp. Typical signs of spoilnge were gas production and off-odor. The identity was determined for about half of the isolates (n = 124) by Analytab Products (API), Biolog, the RiboPrinter System, 16S rDNA sequencing, cellular fatty acid analysis, or some combination of these. The majority of isolates were identified as Clostridium sporogenes (in 33% of products), but Clostridium cochlearium (in 12% of products) and Clostridium tyrobutyricum (in 2% of products) were also retrieved. Similarity analysis of the riboprint patterns for 21 isolates resulted in the identification of 10 ribogroups. A high degree of relatedness was observed between isolates of C. sporogenes originating from products produced 3 years apart, indicating a common and, over time, persistent source of infection. The spoilage potential of 11 well-characterized isolates and two culture collection strains was analyzed by inoculating shrimp cheese spread with single cultures and then storing them at 37°C. Tubes inoculated with C. tyrobutyricum did not show any visible signs of growth (e.g., coagulation, discoloration, gas formation) in the cheese spread. After 2 weeks of incubation, tubes inoculated with C. cochlearium or C. spoprogenes showed gas-holes, syneresis with separation of coagulated casein and liquid, and a change in color of the cheese. The amount of CO2 produced by C. cochlearium strains was approximately one-third that produced by the majority of C. sporogenes strains. To our knowledge, this is the first study to isolate and identify C. cochlearium as a spoilage organism in cheese spread. Copyright ©, International Association for Food Protection.
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| 17. |
- Lövenklev, Maria, et al.
(författare)
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Quantitative interaction effects of carbon dioxide, sodium chloride, and sodium nitrite on neurotoxin gene expression in nonproteolytic Clostridium botulinum type B
- 2004
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 70:5, s. 2928-2934
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Tidskriftsartikel (refereegranskat)abstract
- The effects of carbon dioxide, sodium chloride, and sodium nitrite on type B botulinum neurotoxin (BoNT/B) gene (cntB) expression in nonproteolytic Clostridium botulinum were investigated in a tryptone-peptone-yeast extract (TPY) medium. Various concentrations of these selected food preservatives were studied by using a complete factorial design in order to quantitatively study interaction effects, as well as main effects, on the following responses: lag phase duration (LPD), growth rate, relative cntB expression, and extracellular BoNT/B production. Multiple linear regression was used to set up six statistical models to quantify and predict these responses. All combinations of NaCl and NaNO2 in the growth medium resulted in a prolonged lag phase duration and in a reduction in the specific growth rate. In contrast, the relative BoNT/B gene expression was unchanged, as determined by the cntB-specific quantitative reverse transcription-PCR method. This was confirmed when we measured the extracellular BoNT/B concentration by an enzyme-linked immunosorbent assay. CO2 was found to have a major effect on gene expression when the cntB mRNA levels were monitored in the mid-exponential, late exponential, and late stationary growth phases. The expression of cntB relative to the expression of the 16S rRNA gene was stimulated by an elevated CO2 concentration; the cntB mRNA level was fivefold greater in a 70% CO2 atmosphere than in a 10% CO2 atmosphere. These findings were also confirmed when we analyzed the extracellular BoNT/B concentration; we found that the concentrations were 27 ng·ml -1·unit of optical density-1 in the 10% CO 2 atmosphere and 126 ng·ml-1·unit of optical density-1 in the 70% CO2 atmosphere.
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| 18. |
- Lövenklev, Maria, et al.
(författare)
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Relative neurotoxin gene expression in Clostridium botulinum type B, determined using quantitative reverse transcription-PCR
- 2004
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 70:5, s. 2919-2927
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Tidskriftsartikel (refereegranskat)abstract
- A quantitative reverse transcription-PCR (qRT-PCR) method was developed to monitor the relative expression of the type B botulinum neurotoxin (BoNT/B) gene (cntB) in Clostridium botulinum. The levels of cntB mRNA in five type B strains were accurately monitored by using primers specific for cntB and for the reference gene encoding the 16S rRNA. The patterns and relative expression of cntB were different in the different strains. Except for one of the strains investigated, an increase in cntB expression was observed when the bacteria entered the early stationary growth phase. In the proteolytic strain C. botulinum ATCC 7949, the level of cntB mRNA was four- to fivefold higher than the corresponding levels in the other strains. This was confirmed when we quantified the production of extracellular BoNT/B by an enzyme-linked immunosorbent assay and measured the toxicity of BoNT/B by a mouse bioassay. When the effect of exposure to air on cntB expression was investigated, no decline in the relative expression was observed in spite of an 83% reduction in the viable count based on the initial cell number. Instead, the level of cntB mRNA remained the same. When there was an increase in the sodium nitrite concentration, the bacteria needed a longer adjustment time in the medium before exponential growth occurred. In addition, there was a reduction in the expression of cntB compared to the expression of the 16S rRNA gene at higher sodium nitrite concentrations. This was most obvious in the late exponential growth phase, but at the highest sodium nitrite concentration investigated, 45 ppm, a one- to threefold decline in the cntB mRNA level was observed in all growth phases.
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| 19. |
- Marta, Dora, et al.
(författare)
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Extended staphylococcal enterotoxin D expression in ham products
- 2011
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Ingår i: Food microbiology (Print). - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 28:3, s. 617-620
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcal enterotoxin D (SED) is one of the most frequently recovered enterotoxins in staphylococcal food poisoning (SFP) outbreaks. The expression and production of SED were investigated in three ham products, i.e. boiled ham, smoked ham and dry-cured Serrano ham incubated at room temperature for seven days. . Staphylococcus aureus was also, as a reference, grown in cultivation broth during optimal growth conditions for seven days. In boiled and smoked ham, continuous . sed expression was observed throughout the incubation period with a second increase in . sed expression found after five days of incubation. In smoked ham, nine times less SED per colony-forming unit of . S. aureus was detected than in boiled ham. In boiled ham, the SED levels unpredictably decreased after three days of incubation. In the Serrano ham, SED was detected after five days of incubation although . S. aureus growth was poor and . sed expression was too low to determine. After five days of incubation, all three products contained enough SED to cause SFP. These results show that the specific production levels of SED vary in the different ham products, and that toxin production was in part uncoupled from bacterial growth. © 2010 Elsevier Ltd.
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| 20. |
- Mjönes, Anna-Britta, et al.
(författare)
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Hoarseness and misdirected swallowing in patients with hiatal hernia
- 2007
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Ingår i: European Archives of Oto-Rhino-Laryngology. - : Springer Science and Business Media LLC. - 0937-4477 .- 1434-4726. ; 264:12, s. 1437-1439
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to elucidate whether misdirected swallowing is an extra-laryngeal cause of hoarseness and investigate whether the prevalence of misdirected swallowing and hoarseness in patients with hiatal hernias differ from those with and without pathological gastroesophageal reflux (GER). One hundred and ninety eight patients with hiatal hernias diagnosed via esophageal manometry and pH-reflux test and 262 subjects in the general population who did not have a hiatal hernia at endoscopy, filled in a questionnaire about symptoms on hoarseness, misdirected swallowing, and heartburn. Hoarseness (35%), misdirected swallowing to the larynx (MSL; 35%), misdirected swallowing to the nose (MSN; 22%) and heartburn (85%) were significantly more common in patients with hiatal hernia than in controls (13, 5, 1, and 6%, respectively, P<0.001). MSL and MSN in the patient group were significantly interrelated (P<0.0001). Hoarseness and MSL were not significantly associated (P<0.076). Hoarseness and MSL were as common in the hernia group with normal GER, as in the group with pathological GER. There is a predisposition for hoarseness and MSL in patients with hiatal hernias, but the cause-and-effect relationship is unclear. Hoarseness does not seem to be caused by pathological GER.
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| 21. |
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| 22. |
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| 23. |
- Nielsen, Tim, et al.
(författare)
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The origin of off-odours in packaged rucola (Eruca sativa)
- 2008
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 110:1, s. 96-105
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Tidskriftsartikel (refereegranskat)abstract
- Rucola (Eruca sativa) was decontaminated and then reinoculated with selected microorganisms. The produce was then stored in three different atmospheres and at two temperatures. The accumulation of off-odours in the packaging headspace was analysed. A dozen compounds were detected by olfactometry but only dimethyl sulphide and dimethyl disulphide were considered to have a strong or moderate intensity. Thus, they were identified as the substances causing an unpleasant smell inside the bags. Inoculation with microorganisms resulted in higher production of off-odours. Samples inoculated with Pseudomonadaceae&Xanthamonadaceae were particularly potent in producing the two sulphides. The off-odour problem was much more prominent in samples that were kept in a packaging material that did not allow gas exchange resulting in oxygen levels below 1%. Higher levels of sulphides were detected at 8 °C than at 4 °C. © 2008 Elsevier Ltd. All rights reserved.
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| 24. |
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| 25. |
- Rönner, Anna-Clara, 1971, et al.
(författare)
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Genetic profiling of Campylobacter jejuni strains from humans infected in Sweden or in Thailand, and from healthy Swedish chickens, studied by pulsed-field gel electrophoresis (PFGE).
- 2005
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 37:8, s. 579-584
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Tidskriftsartikel (refereegranskat)abstract
- The major objective of the study was to explore the genomic diversity between Campylobacter jejuni (C.jejuni) from different sources as a tool for epidemiological considerations. Subtyping was performed using pulsed-field gel electrophoresis (PFGE) and the enzyme used for cleavage was SmaI. Isolates originated from humans infected in Sweden (n=49) and Thailand (n=32) and from healthy Swedish chickens (n=51). Eight PFGE groups were formed in a dendrogram and 48% of the isolates belonged to 1 of these groups. In 2 PFGE groups, strains from humans infected in both Sweden and Thailand were represented. Four of the PFGE groups comprised high frequencies of strains from domestic human infection, as well as from healthy chickens. The PFGE pattern was also compared with the antibiotic resistance pattern in all the above-mentioned isolates. In conclusion, C.jejuni was a diverse group based on PFGE genotyping; about 24% of the clones from Swedish patients and healthy Swedish chickens were similar; and there was no correlation between the antibiotic resistance pattern and the PFGE profiling among the studied strains. Our findings are also in accordance with our hypothesis that there may be similarities between Swedish and Thai strains, which might support a theory of globally occurring C.jejuni.
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| 26. |
- Sonesson, Ulf, et al.
(författare)
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Paths to a sustainable food sector: integrated design and LCA of future food supply chains : the case of pork production in Sweden
- 2016
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Ingår i: The International Journal of Life Cycle Assessment. - : Springer Ferlag. - 0948-3349 .- 1614-7502. ; 21:5, s. 664-676
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To describe a more sustainable food sector, a supply chain approach is needed. Changing a supply chain inevitably means that various attributes of the product and its system will change. This project assumed this challenge and delivered detailed descriptions, life cycle assessment (LCA) evaluations, and consequence assessments of the supply chains of six commodities, i.e., milk, cheese, beef, pork, chicken, and bread, from a Swedish region. This paper presents results for the pork supply chain. Methods: In the project setup, experts on production along supply chains designed three scenarios for environmentally improved systems. These scenarios, i.e., the ecosystem, plant nutrients, and climate scenarios, were intended to address different clusters of environmental goals. The next step was to challenge these scenarios by considering their possible consequences for products and systems from the food safety, sensory quality, animal welfare, consumer appreciation, and (for primary production only) cost perspectives. This led to changes in production system design to prevent negative consequences. The final supply chains were quantified using LCA and were again assessed from the three perspectives. Results and discussion: The scenario design approach worked well, thoroughly and credibly describing the production systems. Assessment of consequences bolstered the credibility and quality of the systems and results. The LCA of pig production and smoked ham identified large potentials for improvement by implementing available knowledge: global warming potential (GWP) could be reduced 21–54 % and marine eutrophication by 14–45 %. The main reason for these improvements was improved productivity (approaching the best producers’ current performance), though dedicated measures were also important, resulting in increased nitrogen efficiency, more varied crop rotations for crop production and better production management, and improved animal health and manure management for animal production. Reduced post-farm wastage contributed as did reduced emissions from fertilizer production. Conclusions: The working approach applied was successful in integrating LCA research with food system production expertise to deliver results relevant to supply chain decision-makers. The consequence assessments brought considerable value to the project, giving its results greater credibility. By introducing constraints in the form of “no negative consequences and no increased costs,” the work was “guided” so that the scenario design avoided being hampered by too many opportunities.
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| 27. |
- Staack, N., et al.
(författare)
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Effect of infrared heating on quality and microbial decontamination in paprika powder
- 2008
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 86:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Infrared radiation (IR) was explored as a technique for decontaminating paprika powder. The effect of water activity (aw) and IR heat flux on paprika temperature and water loss were measured during near- or medium-IR heating. Paprika was evaluated in terms of colour, aw, natural flora, and inoculated Bacillus cereus spores. Surface temperatures were considerably higher than temperatures inside the powder, especially at low aw; greater differences were observed with medium- than with near-IR. Surface darkening was observed, though the overall colour was not considerably affected. IR effectively removed water from paprika, especially at aw 0.5 and 0.8, resulting in unsatisfactory spore reduction. However, at aw 0.8, the load of the natural flora was reduced (P < 0.05). In aw 0.96 powder, areas with high remaining aw displayed a reduction >6 log10 CFU/g for B. cereus (P < 0.05). In addition, no microbial counts of the natural background flora were observed in the paprika. © 2007 Elsevier Ltd. All rights reserved.
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| 28. |
- Staack, N., et al.
(författare)
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Effects of temperature, pH, and controlled water activity on inactivation of spores of Bacillus cereus in paprika powder by near-IR radiation
- 2008
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 89:3, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- A process to decontaminate paprika powder using variable near-infrared (IR) radiation was tested using a closed sample holder allowing water to be retained in the powder. The reduction in the concentration of Bacillus cereus spores and changes in water activity (aw) and colour were measured during IR heating. High heat flux was applied initially to heat the powder rapidly to the desired temperature, followed by low heat flux to maintain the temperature for a given time. The water activity (aw) value of the powder could be maintained within the bulk of the closed sample, but the surface aw value decreased during heating. Due to carotenoid sensitivity to temperature, surface and overall colour values declined, though remaining acceptable values of medium red and red, respectively. For powder with an aw value of 0.88 heated to 95-100 °C, the load of B. cereus spores was reduced by 4.5 log10 CFU/g within 6 min; the final spore concentration remained approximately 2 log10 CFU/g due to tailing. Reducing pH to 4.0 from 4.5 did not significantly affect the reduction of the B. cereus spore concentration. © 2008 Elsevier Ltd. All rights reserved.
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| 29. |
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