| 1. |
- Guo, Zhiming, et al.
(författare)
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Label-free surface enhanced Raman scattering spectroscopy for discrimination and detection of dominant apple spoilage fungus
- 2021
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Ingår i: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 338
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Tidskriftsartikel (refereegranskat)abstract
- Fungal infection is one of the main causes of apple corruption. The main dominant spoilage fungi in causing apple spoilage are storage mainly include Penicillium Paecilomyces paecilomyces (P. paecilomyces), penicillium chrysanthemum (P. chrysogenum), expanded Penicillium expansum (P. expansum), Aspergillus niger (Asp. niger) and Alternaria. In this study, surface-enhanced Raman spectroscopy (SERS) based on gold nanorod (AuNRs) substrate method was developed to collect and examine the Raman fingerprints of dominant apple spoilage fungus spores. Standard normal variable (SNV) was used to pretreat the obtained spectra to improve signal-tonoise ratio. Principal component analysis (PCA) was applied to extract useful spectral information. Linear discriminant analysis (LDA) and non-linear pattern recognition methods including K nearest neighbor (KNN), Support vector machine (SVM) and back propagation artificial neural networks (BPANN) were used to identify fungal species. As the comparison of modeling results shown, the BPANN model established based on the characteristic spectra variables have achieved the satisfactory result with discrimination accuracy of 98.23%; while the PCA-LDA model built using principal component variables achieved the best distinguish result with discrimination accuracy of 98.31%. It was concluded that SERS has the potential to be an inexpensive, rapid and effective method to detect and identify fungal species.
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| 2. |
- Ngo, Hai Hoang Tuan, et al.
(författare)
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Effect of light-touch intervention and associated factors to microbial contamination at small-scale pig slaughterhouses and traditional pork shops in Vietnam
- 2023
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Ingår i: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- Traditional pork value chains dominate the production and distribution of pork in Vietnam; however, the high level of microbiological contamination in pork may increase the risk of food-borne disease for consumers. There is limited evidence about how to feasibly and scalably reduce microbial contamination in pork sold in traditional markets. This study aimed to assess the effectiveness of light-touch interventions for changing worker behaviour in small-scale slaughterhouses and vendors at traditional pork shops, as well as to identify risk factors for pork contamination. The intervention packages consisted of providing hygiene tools and delivering a food safety training which had been designed in a participatory way and covered 10 small-scale slaughterhouses and 29 pork shops. Pig carcasses, retailed pork, contact surfaces, and hands were sampled to measure the total bacterial count (TBC) and Salmonella contamination before, three and six weeks after the intervention, and trainee practices were observed at the same time. Linear and generalized linear mixed effects models were constructed to identify risk factors for TBC and Salmonella contamination at the slaughterhouses and pork shops. The interventions at slaughterhouses and pork shops both showed a slight reduction of TBC contamination in pig carcasses and Salmonella prevalence in retailed pork, while the TBC in retailed pork decreased only marginally. For slaughterhouses, the regression model indicated that smoking or eating during slaughtering (indicating poor hygienic practices) was associated with TBC increasing, while cleaning floors and wearing boots reduced TBC contamination. For pork shops, using rough materials (cardboard or wood) to display pork was the only factor increasing TBC contamination in pork, whereas cleaning knives was associated with lower TBC. Besides, the presence of supporters and wearing aprons reduced the probability of Salmonella contamination in pork. The findings highlight the effectiveness of light-touch interventions in reducing microbial contamination in pig carcasses at small-scale slaughterhouses and pork at traditional shops over the study period.
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| 3. |
- Ngo, Hai Hoang Tuan, et al.
(författare)
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Microbial contamination and associated risk factors in retailed pork from key value chains in Northern Vietnam
- 2021
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Ingår i: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 346
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Tidskriftsartikel (refereegranskat)abstract
- Pork and pork products are important staple food in the diet of Vietnamese consumers. The safety of pork, including biological contamination, is a concern to several public authorities and value chain actors. This crosssectional study aimed to identify Salmonella and total bacterial count (TBC) contamination of cut pork sold in different outlets, and determine the potential factors leading to contamination. A total of 671 pork samples were collected from different retail channels in three provinces in Northern Vietnam. Hygiene conditions and practices at pork vending premises were also observed and recorded. Data analysis used descriptive statistics and regression analysis. Overall, Salmonella prevalence in retailed pork was 58.1%. Salmonella contamination in pork from traditional retail, modern retail and food services were 60.5%, 50.9% and 80.5%, respectively. Eighty percent and 68% of fresh pork in canteen and street food was contaminated with Salmonella. Only a small proportion of a subset of the pork samples (6.2%) tested met the Vietnamese standard requirement for TBC contamination. Average concentration of TBC in fresh pork in traditional retail, modern retail and food services were 6.51 (SD: 0.64), 6.38 (0.65), and 6.96 (0.85) LogCFU/g, respectively. Transport time, use of the same tools for pork and other types of meat, storage temperature, and environment hygiene are important factors that might affect microbial contamination. The findings underline the high level of microbial contamination, which requires practical interventions to improve food safety hygiene practices and behavior of pork retailers.
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| 4. |
- Ngo, Hoang Tuan Hai, et al.
(författare)
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Assessment of a light-touch intervention to reduce microbial contamination at small-scale pig slaughterhouses and traditional pork shops in Vietnam
- 2023
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- Traditional pork value chains dominate the production and distribution of pork in Vietnam; however, there high microbiological contamination of pork may lead to health risks. There is limited evidence about how to sustainably and scalably reduce microbial contamination in pork sold in traditional markets. This study aimed to assess the effectiveness of light-touch interventions for changing worker behaviour in small-scale slaughterhouses and retailers at traditional pork shops, as well as to identify risk factors for pork contamination. The intervention packages consisted of providing hygiene tools and delivering a food safety training which had been designed in a participatory way and covered 10 small-scale slaughterhouses and 29 pork shops. Pig carcasses, retailed pork, contact surfaces, and hands were sampled to measure the total bacterial count (TBC) and Salmonella contamination and trainee practices were observed before, three and six weeks after the intervention. Linear and generalized linear mixed effects models were constructed to identify risk factors for TBC and Salmonella contamination at the slaughterhouses and pork shops. Intervention results showed a slight reduction of TBC contamination in pig carcasses from 4.46 to 4.23 log10 CFU/cm2 (p = 0.09) and Salmonella prevalence in retailed pork (reduction from 52% to 24% detection, p = 0.08), while the TBC in retailed pork decreased only marginally (5.47 vs. 5.36 log10 CFU/g, p = 0.23). For slaughterhouses, the regression model indicated that smoking or eating during slaughtering was a risk factor, associated with TBC increasing by 0.60 log10 CFU/g (95% confidence interval (CI): 0.12 to 0.96, p =0.02), while cleaning floors and wearing boots reduced TBC contamination with 0.53 log10 CFU/g (CI: –0.83 to 0.01, p = 0.03) and 1.04 log10 CFU/g (CI: –1.50 to –0.26, p = 0.03), respectively. For pork shops, using rough materials (cardboard or wood) to display pork was the only factor increasing TBC contamination in pork with 0.57 log10 CFU/g (CI: 0.22 to 0.91, p < 0.001), whereas wearing aprons was associated with lower TBC, with 0.45 log10 CFU/g (CI: –0.79 to –0.12, p = 0.02), and Salmonella contamination in pork (odds ratio (OR) = 0.13, CI: 0.02 to 0.72, p = 0.03). The findings highlight the effectiveness of light-touch interventions in reducing microbial contamination in pig carcasses and pork over the study period.
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| 5. |
- Persson, Sofia, et al.
(författare)
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Comparison between RT droplet digital PCR and RT real-time PCR for quantification of noroviruses in oysters.
- 2018
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 284, s. 73-83
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Tidskriftsartikel (refereegranskat)abstract
- Oysters are frequently associated with norovirus outbreaks, but the presence of norovirus RNA in oysters does not necessarily imply a health risk to humans. There is a close link between human illness and consumption of oysters with high levels of norovirus RNA, but oysters with low levels of norovirus RNA are more unlikely to be associated with illness. Reliable and precise quantification methods are therefore important for outbreak investigations and risk assessments. This study optimised and validated RT droplet digital PCR (RT-ddPCR) assays for quantification of norovirus genogroups I and II in artificially contaminated oysters, and compared them with the standard method, RT real-time PCR (RT-qPCR). The two methods had comparable 95% limits of detection, but RT-ddPCR generally showed greater precision in quantification. Differences between fluorometric measurements and quantification with RT-ddPCR were determined on in vitro transcribed RNA with targets for norovirus genogroups I and II. Quantification by RT-ddPCR was on average 100 times lower than the fluorometric value for norovirus GI and 15.8 times lower than the fluorometric value for norovirus GII. The large inter-assay difference observed highlights the need for monitoring the RT efficiency in RT-ddPCR, especially when results from different assays are compared. Overall, this study suggests that RT-ddPCR can be a suitable method for precise quantification of norovirus genogroups I and II in oysters.
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| 6. |
- Persson, Sofia, et al.
(författare)
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Optimisation and evaluation of an automated system for extraction of viral RNA from oysters
- 2020
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Ingår i: International Journal of Food Microbiology. - : ELSEVIER. - 0168-1605 .- 1879-3460. ; 315
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Tidskriftsartikel (refereegranskat)abstract
- The NucliSENS MiniMAG (Minimag) system from bioMerieux is widely used for extraction of viral RNA from oysters and is included as informative material in the ISO method for quantification of hepatitis A virus (HAV) and norovirus genogroups I and II (GI and GII) in food (ISO 15216-1:2017). However, the system is no longer on sale within the EU and alternative methods are therefore needed. We optimised and evaluated an automated benchtop system for extraction of viral RNA from oysters artificially contaminated with HAV, norovirus GI, norovirus GII and mengovirus, using the same reagents and a similar protocol as with the Minimag method. Using the automated system instead of Minimag increased measured viral concentration by on average 1.3 times, suggesting that the automated system extracts viral RNA more efficiently than Minimag. A drawback with the automated system was that it displayed higher variability in measured concentration for mengovirus. The median viral recovery was 17%, 37%, 44% and 41% for samples extracted with the automated system and 15%, 27%, 34% and 23% for samples extracted with Minimag for HAV, norovirus GI, norovirus GII and mengovirus, respectively. All samples displayed < 75% inhibition in RT-qPCR when extracted with the automated system or Minimag. Together, these results suggest that the automated system can be a suitable alternative to Minimag in analysis of HAV, norovirus GI and norovirus GII in oysters. However, verification using naturally contaminated oysters is needed before it can be used for food safety control purposes.
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| 7. |
- Olsen, M, et al.
(författare)
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Quality control of two rose bengal and modified DRBC and DG18 media
- 1997
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Ingår i: INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY. - : ELSEVIER SCIENCE BV. - 0168-1605. ; 35:2, s. 163-168
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The effect of storage on the performance of four mycological media, DG18, DRBC and two Rose Bengal agars, one from Difco, the other recommended by the Swedish Standard Institution, was investigated. The autoclaved media were stored (+4 degrees C) in the d
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