| 1. |
- Canaviri Paz, Pamela, et al.
(författare)
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Safeguarding of quinoa beverage production by fermentation with Lactobacillus plantarum DSM 9843
- 2020
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605. ; 324
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Tidskriftsartikel (refereegranskat)abstract
- Plant-based beverages are increasing in popularity and quinoa is an attractive option. A hygienic implication linked to the production of beverages from raw material originating from plants is the high microbial contamination. The safety of the product can be guaranteed by lactic acid fermentation, and by using a probiotic strain as starter culture for the fermentation, the final product will benefit from a high number of live probiotics. In this study, a commercial probiotic strain was used for fermentation of a quinoa-based beverage. White quinoa grains were boiled, mixed with water and pasteurized before the beverage was fermented by Lactobacillus plantarum DSM 9843 at 30 °C for 2 days and then stored at 4 °C for 28 days. pH and production of D- and L-lactic acid were monitored, and viable counts were performed for total aerobes, Lactobacillus and Enterobacteriaceae. Colonies from countable plates were randomly picked and in total 335 isolates were identified by 16S rRNA gene sequencing. After heat treatment isolates of Enterobacter, Salmonella, Escherichia, Pantoea, Enterococcus, Klebsiella, and Leclercia were found in the heat-treated but unfermented quinoa beverage. After fermentation pH has decreased below 4, Enterobacteriaceae count was below detection limit and the Lactobacillus count was high 10.6 log CFU/ml (10.3–10.8) (p = 0.002 compared to inoculated counts). During storage pH and the concentration of lactic acid remained stable but after 28 days the lactobacilli count had decreased to 6.9 (6.6–7.2) (p = 0.065 compared to inoculated counts). The majority of isolates picked from Rogosa and Tryptic Soy Agar was identified as Lactobacillus plantarum but 19% and 6% were identified as Enterococcus mudtii and Pediococcus pentosaceous, respectively. The fermentation process applied improved the safety and stability of the product and fortified it with a high content of live probiotics. A safety problem is the spontaneous growth of enterococci (Enterococcus mudtii) during fermentation, enterococci originating from the native quinoa. A solution to this problem can be to increase the rate of the lactic acid fermentation, e.g. by using a higher inoculum of a more active starter culture, and/or to use a starter culture more antagonistic toward enterococci.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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. - 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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| 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. |
- Uhlig, E., et al.
(författare)
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The live bacterial load and microbiota composition of prepacked “ready-to-eat” leafy greens during household conditions, with special reference to E. coli
- 2022
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605. ; 377
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Tidskriftsartikel (refereegranskat)abstract
- Ready-to-eat (RTE) leafy greens are popular products that unfortunately have been associated with numerous foodborne illness outbreaks. Since the influence of consumer practices is essential for their quality and safety, the objective of this study was to analyze the microbiota of RTE products throughout shelf life during simulated household conditions. Products from different companies were analyzed in terms of plate counts, and resealed and unopened packages were compared. High bacterial loads were found, up to a total plate count of 9.6 log10 CFU/g, and Enterobacteriaceae plate counts up to 6.0 CFU/g on the expiration date. The effect of consumer practice varied, thus no conclusions regarding resealed or unopened bags could be drawn. The tested products contained opportunistic pathogens, such as Enterobacter homaechei, Hafnia paralvei and Pantoea agglomerans. Amplicon sequencing revealed that the relative abundance of major taxonomic groups changed during shelf life; Pseudomonadaceae and Xanthomonadaceae decreased, while Flavobacteriaceae and Marinomonadaceae inceased. Inoculation with E. coli CCUG 29300T showed that the relative abundance of Escherichia-Shigella was lower on rocket than on other tested leafy greens. Inoculation with E. coli strain 921 indicate growth at the beginning of shelf-life time, while E. coli 731 increases at the end, seemingly able to adapt to cold storage conditions. The high levels of live microorganisms, the detection of opportunistic pathogens, and the ability of E. coli strains to grow at refrigeration temperature raise concerns and indicate that the shelf life may be shortened to achieve a safer product. Due to variations between products, further studies are needed to define how long the shelf-life of these products should be, to ensure a safe product even at the end of the shelf-life period.
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