Persistent and Emerging Issues in the Safety of Fresh Fruit and Vegetables

A special issue of Agriculture (ISSN 2077-0472).

Deadline for manuscript submissions: closed (15 February 2015) | Viewed by 40048

Special Issue Editors


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Guest Editor
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97 South, Summerland, BC, Canada
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97 South, Summerland, BC, Canada
Interests: food microbiology; safety of horticultural products; viable but non culturable state in human pathogens; effects of stress on human pathogens (Salmonella; STEC)

Special Issue Information

Dear Colleagues,

Reports from international public health authorities indicate that infections attributed to the consumption of fresh produce contribute significantly to the global burden of foodborne disease. There are also concerns that expansion in trade, increasing supply chain complexity, changes in production systems or shifts in the geographic distribution of pathogens due to climate change could favor the emergence or re-emergence of infectious bacterial, viral or parasitic species that may contaminate fresh fruits and vegetables. Information on the origin, prevalence, characteristics and fate of such pathogens during the production, processing, storage and distribution of fresh produce is therefore needed to mitigate current and anticipated threats to food safety. While considerable research has been devoted to the examination of issues consequent to contamination with enteric bacterial pathogens, important gaps in knowledge remain. In addition, the on-going scarcity of scientific information about viral and parasitic foodborne pathogens and their behavior in fresh fruits and vegetables hinders efforts to assess the implied risks and the development of effective interventions.

Prof. Dr. Pascal Delaquis
Dr. Susan Bach
Guest Editors

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Keywords

  • bacteria
  • parasites
  • viruses
  • fresh produce
  • intervention
  • disinfection
  • microbial risk assessment
  • public health

Published Papers (5 papers)

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Research

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3583 KiB  
Article
Microarray-Based Screening of Differentially Expressed Genes of E. coli O157:H7 Sakai during Preharvest Survival on Butterhead Lettuce
by Inge Van der Linden, Bart Cottyn, Mieke Uyttendaele, Geertrui Vlaemynck, Marc Heyndrickx, Martine Maes and Nicola Holden
Agriculture 2016, 6(1), 6; https://0-doi-org.brum.beds.ac.uk/10.3390/agriculture6010006 - 26 Jan 2016
Cited by 13 | Viewed by 5979
Abstract
Numerous outbreaks of Escherichia coli O157:H7 have been linked to the consumption of leafy vegetables. However, up to the present, little has been known about E. coli O157:H7’s adaptive responses to survival on actively growing (and thus responsive) plants. In this study, whole [...] Read more.
Numerous outbreaks of Escherichia coli O157:H7 have been linked to the consumption of leafy vegetables. However, up to the present, little has been known about E. coli O157:H7’s adaptive responses to survival on actively growing (and thus responsive) plants. In this study, whole genome transcriptional profiles were generated from E. coli O157:H7 cells (isolate Sakai, stx-) one hour and two days after inoculation on the leaves of growing butterhead lettuce, and compared with an inoculum control. A total of 273 genes of E. coli O157:H7 Sakai (5.04% of the whole genome) were significantly induced or repressed by at least two-fold (p < 0.01) in at least one of the analyzed time points in comparison with the control. Several E. coli O157:H7 genes associated with oxidative stress and antimicrobial resistance were upregulated, including the iron-sulfur cluster and the multiple antibiotic resistance (mar) operon, whereas the Shiga toxin virulence genes were downregulated. Nearly 40% of the genes with significantly different expression were poorly characterized genes or genes with unknown functions. These genes are of special interest for future research as they may play an important role in the pathogens’ adaptation to a lifestyle on plants. In conclusion, these findings suggest that the pathogen actively interacts with the plant environment by adapting its metabolism and responding to oxidative stress. Full article
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210 KiB  
Article
Evaluation of Single or Double Hurdle Sanitizer Applications in Simulated Field or Packing Shed Operations for Cantaloupes Contaminated with Listeria monocytogenes
by Cathy C. Webb, Marilyn C. Erickson, Lindsey E. Davey and Michael P. Doyle
Agriculture 2015, 5(2), 231-244; https://0-doi-org.brum.beds.ac.uk/10.3390/agriculture5020231 - 28 Apr 2015
Cited by 7 | Viewed by 5341
Abstract
Listeria monocytogenes contamination of cantaloupes has become a serious concern as contaminated cantaloupes led to a deadly outbreak in the United States in 2011. To reduce cross-contamination between cantaloupes and to reduce resident populations on contaminated melons, application of sanitizers in packing shed [...] Read more.
Listeria monocytogenes contamination of cantaloupes has become a serious concern as contaminated cantaloupes led to a deadly outbreak in the United States in 2011. To reduce cross-contamination between cantaloupes and to reduce resident populations on contaminated melons, application of sanitizers in packing shed wash water is recommended. The sanitizing agent of 5% levulinic acid and 2% sodium dodecyl sulfate (SDS) applied as a single hurdle in either a simulated dump or dip treatment significantly reduced L. monocytogenes to lower levels at the stem scar compared to a simulated dump treatment employing 200 ppm chlorine; however pathogen reductions on the rind tissue were not significantly different. Double hurdle approaches employing two sequential packing plant treatments with different sanitizers revealed decreased reduction of L. monocytogenes at the stem scar. In contrast, application of sanitizers both in the field and at the packing plant led to greater L. monocytogenes population reductions than if sanitizers were only applied at the packing plant. Full article
1720 KiB  
Article
Effect of Ozone Treatment on Inactivation of Escherichia coli and Listeria sp. on Spinach
by Shreya Wani, Jagpreet K. Maker, Joseph R. Thompson, Jeremy Barnes and Ian Singleton
Agriculture 2015, 5(2), 155-169; https://0-doi-org.brum.beds.ac.uk/10.3390/agriculture5020155 - 26 Mar 2015
Cited by 37 | Viewed by 11842
Abstract
The efficacy of “gaseous” ozone in reducing numbers and re-growth of food-borne pathogens, (Escherichia coli and Listeria spp.), on leafy salads was investigated using spinach. A preliminary in vivo study showed 1-log reduction in six strains of E. coli and two species [...] Read more.
The efficacy of “gaseous” ozone in reducing numbers and re-growth of food-borne pathogens, (Escherichia coli and Listeria spp.), on leafy salads was investigated using spinach. A preliminary in vivo study showed 1-log reduction in six strains of E. coli and two species of Listeria spp. on spinach exposed to 1 ppm ozone for 10 min. A range of ozone treatments were explored to deliver optimal bacterial inactivation while maintaining the visual appearance (color) of produce. Exposure to a higher ozone concentration for a shorter duration (10 ppm for 2 min) significantly reduced E. coli and Listeria spp. viable counts by 1-log and the pathogens did not re-grow following treatment (over a nine-day storage period). Impacts of 1 and 10 ppm ozone treatments were not significantly different. Approximately 10% of the pathogen population was resistant to ozone treatment. We hypothesized that cell age may be one of several factors responsible for variation in ozone resistance. E. coli cells from older colonies demonstrated higher ozone resistance in subsequent experiments. Overall, we speculate that gaseous ozone treatment constitutes the basis for an alternative customer-friendly method to reduce food pathogen contamination of leafy produce and is worth exploring on a pilot-scale in an industrial setting. Full article
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1311 KiB  
Article
Food Safety Information Processing and Teaching Behavior of Dietitians: A Mental Model Approach
by Lydia C. Medeiros and Jeffrey T. LeJeune
Agriculture 2015, 5(1), 132-154; https://0-doi-org.brum.beds.ac.uk/10.3390/agriculture5010132 - 18 Mar 2015
Cited by 3 | Viewed by 8193
Abstract
Health professionals play an important role in educating the public about food safety risks. However, the ways this important group of educators remains up-to-date on these topics are not well defined. In this study, a national sample of dietitians employed in direct teaching [...] Read more.
Health professionals play an important role in educating the public about food safety risks. However, the ways this important group of educators remains up-to-date on these topics are not well defined. In this study, a national sample of dietitians employed in direct teaching of patients (n = 327) were recruited to complete a web-delivered survey designed to develop a model of factors that promote information processing and teaching in practice about food safety related to fresh vegetables. The resulting mental model demonstrates that dietitians teach fresh vegetable safety using systematic information processing to intellectually understand new information, but this is also associated with a gap in the dietitian’s knowledge of food safety. The juxtaposition of an information processing model with a behavioral model provides valuable new insights about how dietitians seek, acquire and translate/transfer important information to move patients toward a higher goal of food safety. The study also informs food safety educators as they formulate teaching strategies that are more effective than other approaches at promoting behavior change. Full article
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Review

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230 KiB  
Review
Emerging Perspectives on the Natural Microbiome of Fresh Produce Vegetables
by Colin R. Jackson, Bram W. G. Stone and Heather L. Tyler
Agriculture 2015, 5(2), 170-187; https://0-doi-org.brum.beds.ac.uk/10.3390/agriculture5020170 - 03 Apr 2015
Cited by 48 | Viewed by 7980
Abstract
Plants harbor a diverse microbiome existing as bacterial populations on the leaf surface (the phyllosphere) and within plant tissues (endophytes). The composition of this microbiome has been largely unexplored in fresh produce vegetables, where studies have tended to focus on pathogen detection and [...] Read more.
Plants harbor a diverse microbiome existing as bacterial populations on the leaf surface (the phyllosphere) and within plant tissues (endophytes). The composition of this microbiome has been largely unexplored in fresh produce vegetables, where studies have tended to focus on pathogen detection and survival. However, the application of next-generation 16S rRNA gene sequencing approaches is beginning to reveal the diversity of this produce-associated bacterial community. In this article we review what is known about the composition of the microbiome of fresh produce vegetables, placing it in the context of general phyllosphere research. We also demonstrate how next-generation sequencing can be used to assess the bacterial assemblages present on fresh produce, using fresh herbs as an example. That data shows how the use of such culture-independent approaches can detect groups of taxa (anaerobes, psychrophiles) that may be missed by traditional culture-based techniques. Other issues discussed include questions as to whether to determine the microbiome during plant growth or at point of purchase or consumption, and the potential role of the natural bacterial community in mitigating pathogen survival. Full article
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