| 1. |
- Mogren, Lars, et al.
(författare)
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The hurdle approach-A holistic concept for controlling food safety risks associated with pathogenic bacterial contamination of leafy green vegetables. A review
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 9:AUG
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Forskningsöversikt (refereegranskat)abstract
- Consumers appreciate leafy green vegetables such as baby leaves for their convenience and wholesomeness and for adding a variety of tastes and colors to their plate. In Western cuisine, leafy green vegetables are usually eaten fresh and raw, with no step in the long chain from seed to consumption where potentially harmful microorganisms could be completely eliminated, e.g., through heating. A concerning trend in recent years is disease outbreaks caused by various leafy vegetable crops and one of the most important foodborne pathogens in this context is Shiga toxin-producing Escherichia coli (STEC). Other pathogens such as Salmonella, Shigella, Yersinia enterocolitica and Listeria monocytogenes should also be considered in disease risk analysis, as they have been implicated in outbreaks associated with leafy greens. These pathogens may enter the horticultural value network during primary production in field or greenhouse via irrigation, at harvest, during processing and distribution or in the home kitchen/restaurant. The hurdle approach involves combining several mitigating approaches, each of which is insufficient on its own, to control or even eliminate pathogens in food products. Since the food chain system for leafy green vegetables contains no absolute kill step for pathogens, use of hurdles at critical points could enable control of pathogens that pose a human health risk. Hurdles should be combined so as to decrease the risk due to pathogenic microbes and also to improve microbial stability, shelf-life, nutritional properties and sensory quality of leafy vegetables. The hurdle toolbox includes different options, such as physical, physiochemical and microbial hurdles. The goal for leafy green vegetables is multi-target preservation through intelligently applied hurdles. This review describes hurdles that could be used for leafy green vegetables and their biological basis, and identifies prospective hurdles that need attention in future research.
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| 2. |
- Darlison, Julia, et al.
(författare)
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Leaf mineral content govern microbial community structure in the phyllosphere of spinach (Spinacia oleracea) and rocket (Diplotaxis tenuifolia)
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 1879-1026 .- 0048-9697. ; 675, s. 501-512
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Tidskriftsartikel (refereegranskat)abstract
- The plant microbiome is an important factor for plant health and productivity. While the impact of nitrogen (N) availability for plant growth and development is well established, its influence on the microbial phyllosphere community structure is unknown. We hypothesize that nitrogen impacts the growth and abundance of several microorganisms on the leaf surface. The bacterial and fungal communities of baby leaf spinach (Spinacia oleracea), and rocket (Diplotaxis tenuifolia) were investigated in a field trial for two years in a commercial setting. Nitrogen fertilizer was tested in four doses (basic nitrogen, basic + suboptimal, basic + commercial, basic + excess) with six replicates in each. Culture-independent (Illumina sequencing) and culture-dependent (viable count and identification of bacterial isolates) community studies were combined with monitoring of plant physiology and site weather conditions. This study found that alpha diversity of bacterial communities decreased in response to increasing nitrogen fertilizer dose, whereas viable counts showed no differences. Correspondingly, fungal communities of the spinach phyllosphere showed a decreasing pattern, whereas the decreasing diversity of fungal communities of rocket was not significant. Plant species and effects of annual variations on microbiome structure were observed for bacterial and fungal communities on both spinach and rocket. This study provides novel insights on the impact of nitrogen fertilizer regime on a nutrient scarce habitat, the phyllosphere.
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| 3. |
- Darlison, Julia
(författare)
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Microbial community dynamics in the phyllosphere of leafy vegetables
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microbes interact with the phyllosphere creating a plant microbiota holobiont. From a food safety aspect the phyllosphere is especially important in leafy vegetables which are generally consumed raw. Plant-microbe interactions are complex, but well-known ecological concepts can be applied to explain the dynamics. The microbial communities in the phyllosphere of spinach, rocket and Swiss chard were studied in field and greenhouse studies in this thesis. We examined the impact of nitrogen fertiliser application to plants on the microbiota in the phyllosphere. The influence of nitrogen fertiliser on establishment of an invading human pathogen, Escherichia coli O157:H7 gfp+ and the role of the plant species and plant cultivar were investigated. We explored the succession of microbial communities on leafy vegetables. To identify the microbial communities, culture-independent methods (Illumina MiSeq after DNA extraction from the leaf surface) and culture dependent methods (viable count and identification of bacterial isolates with 16S rRNA sequencing) were used in combination with plant physiological measurements and weather monitoring.Plant species, environmental factors and annual variations had selective effects on the microbial communities in the phyllosphere. Increasing nitrogen supply reduced microbial diversity, as did harvesting the leaves. The concept of prevention of invasion by high diversity was not confirmed for bacterial communities in the phyllosphere. Phyllosphere microorganisms are also of interest for possibly developing new efficient and sustainable methods in agriculture and horticulture, however, before microbiomes can be exploited, more knowledge is needed about how plants and microbes interact with the environment, management and post-harvest procedures.
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| 4. |
- Darlison, Julia, et al.
(författare)
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Plant species affects establishment of Escherichia coli O157:H7 gfp+ on leafy vegetables
- 2019
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 127, s. 292-305
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Tidskriftsartikel (refereegranskat)abstract
- Aims Greenhouse trials were conducted with different cultivars of baby leaf spinach, rocket and Swiss chard and inoculation of Escherichia coli O157:H7 gfp+, to determine whether plant species and cultivar have an impact on the establishment of this strain. Methods and Results Three cultivars each of spinach, rocket and Swiss chard were spray inoculated with E. coli O157:H7 gfp+ at doses of log 7 CFU per ml. Due to the different lengths of growing period spinach and Swiss chard were spray inoculated three times and rocket five times, with final inoculation performed 3 days prior to harvest. After a growing period of 26-33 days, E. coli O157:H7 gfp+ was recovered from the leaf surface in mean populations between log 1 and 6 CFU per gram. The lowest occurrence of E. coli O157:H7 gfp+ was found on rocket leaves and the highest on spinach. There was no significant difference in the establishment of E. coli O157:H7 gfp+ between cultivars, but there were differences between plant species. Indigenous phyllosphere bacteria were pure cultured and identified with 16S rRNA gene sequencing. Conclusions Despite the same high inoculation dose of E. coli O157:H7 gfp+ on leaves, the establishment rate differed between plant species. However, plant cultivar did not affect establishment. Pantoea agglomerans dominated the identified bacterial isolates. Significance and Impact of the Study As previous studies are inconclusive on choice of model plant species and cultivar, we studied whether plant species or cultivar determines the fate of E. coli O157:H7 gfp+ on leafy vegetables. The findings indicate that plant species is a key determinant in the establishment of E. coli O157:H7 gfp+.
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| 5. |
- Darlison, Julia
(författare)
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Sensorisk profilering av svenskproducerade vita viner och en omvärldsanalys av svensk vinodling
- 2014
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Intresse för att undersöka den sensoriska profilen av svenskproducerade vita viner finns då det är en ny produkt och det råder brist på undersökningar. Det finns även behov av att skapa en utgångspunkt för att underlätta framtida utveckling och beskrivning av den sensoriska profilen av svenskproducerade vita viner. Även genom intervjuer med såväl vinodlare som vinexperter undersöktes de båda gruppernas åsikter om den svenska vinsektorn. Den sensoriska profilen framtagen i den här studien visar att vitt vin producerat från svenskodlade druvor har en frisk, citrus och blommig doft och en frisk smak av citrus och gröna äpple. Genom att se till utvecklingen hos länder med nystartad vinproduktion med liknande klimat som Sverige, som England och Kanada, kan inspiration ges för hur Sveriges vinsektor kan utvecklas.
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| 6. |
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| 7. |
- Nordmark, Lotta, et al.
(författare)
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The Nordic Light Terroir
- 2016
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Ingår i: 29th International Horticultural Congress on Horticulture: Sustaining Lives, Livelihoods and Landscapes (IHC 2014): 4th International Symposium on Tropical Wines and International Symposium on Grape and Wine Production in Diverse Regions. - 0567-7572 .- 2406-6168. - 9789462611108 ; 1115, s. 189-193
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Bokkapitel (refereegranskat)abstract
- Grapes are culturally a new crop in the Swedish landscape, which demands an introduction period concerning development of knowledge about how to grow the wine. Climate changes together with the development of "cross breeding" in Vitis vinifera open up new possibilities with new grapes, that previously were not possible to grow commercially and that suits the Swedish consumers. Wine production is of great interest among growers, producers and consumers. Experiences from regions with the same climate as Sweden show that production of quality wines is possible. Sweden was appointed as EU official wine country in 1999. There is a lack of tradition and experience of commercial cultivation of grapes, but Sweden has 300 vineyards including 15 to 25 vineyards approved by the authorities. A project started in the winter 2013 with the aim to increase the knowledge about grapevine growing and wine production with the Swedish and Nordic Light Terroir as background. A study where researchers from disciplines like agriculture, chemistry, yeast/microbiology, process engineering, sensorial analysis and market analysis collaborates. We have started to study the micro climate at Hällåkra vineyard and different types of grapes/crops and vineyards management that suits the Swedish and Nordic Light Terroir. A sensory analysis was made of Swedish white wines trying to identify The Nordic Light Terroir attributes. The Sensory profile of white wine from Solaris grown in Sweden is as we found a wine with a fresh, citrus and flowery aroma and a fresh, citrus and green apple taste. The wine's body will grow with increased knowledge of the entire chain; from soil to bottle based on the knowledge-building the new beverage platform will assist with.
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| 8. |
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| 9. |
- Rosberg, Anna Karin, et al.
(författare)
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Commercial wash of leafy vegetables do not significantly decrease bacterial load but leads to shifts in bacterial species composition
- 2021
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Ingår i: Food Microbiology. - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 94
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Tidskriftsartikel (refereegranskat)abstract
- Production of leafy vegetables for the "Ready-to-eat"-market has vastly increased the last 20 years, and consumption of these minimally processed vegetables has led to outbreaks of food-borne diseases. Contamination of leafy vegetables can occur throughout the production chain, and therefore washing of the produce has become a standard in commercial processing. This study explores the bacterial communities of spinach (Spinacia oleracea) and rocket (Diplotaxis tenuifolia) in a commercial setting in order to identify potential contamination events, and to investigate effects on bacterial load by commercial processing. Samples were taken in field, after washing of the produce and at the end of shelf-life. This study found that the bacterial community composition and diversity changed significantly from the first harvest to the end of shelf-life, where the core microbiome from the first to the last sampling constituted <2% of all OTUs. While washing of the produce had no reducing effect on bacterial load compared to unwashed, washing led to a change in species composition. As the leaves entered the cold chain after harvest, a rise was seen in the relative abundance of spoilage bacteria. E. coli was detected after the washing indicating issues of cross-contamination in the wash water.
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| 10. |
- Vågsholm, Ivar, et al.
(författare)
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Safety risks associated with dispersal of E. coli O157:H7 in home sprouting modules
- 2019
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Ingår i: Food Science and Technology. - : Elsevier BV. - 0023-6438 .- 1096-1127. ; 101, s. 783-788
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Tidskriftsartikel (refereegranskat)abstract
- Despite numerous outbreaks of foodborne illnesses associated with sprouts, consumption of raw sprouted seeds is still linked with a healthy lifestyle in Scandinavia. Different types of sprouting modules for home sprout production are available on the market, and sold without information about risks associated with sprouting. During sprouting, conditions are ideal for seed emergence, but also for bacterial proliferation. Moreover, since seeds used for sprouting are non-sterile, human pathogens may propagate within sprouting modules. This study assessed vertical dispersal of Escherichia coli strain O157:H7 in two types of three-layered sprouting modules intended for home sprouting. Organic fenugreek seeds were artificially inoculated and transferred to either the top or bottom layer of sprouting modules. As commensal bacterial biota can affect survival of an artificially introduced strain, but can also contain pathogens, culturable bacterial species on fenugreek seeds were evaluated. A Beta-Poisson model was used to assess the risk of consumer exposure to the artificially introduced strain when added to seeds in the top or bottom layer. We found that the inoculated strain dispersed vertically up and down between the layers and that the risk of bacterial dispersal was high in either direction, posing a high risk of consumer exposure.
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