Browsing by Subject "food safety"

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  • Ahlberg, Sara; Randolph, Delia; Okoth, Sheila; Lindahl, Johanna (2019)
    Aflatoxins continue to be a food safety problem globally, especially in developing regions. A significant amount of effort and resources have been invested in an attempt to control aflatoxins. However, these efforts have not substantially decreased the prevalence nor the dietary exposure to aflatoxins in developing countries. One approach to aflatoxin control is the use of binding agents in foods, and lactic acid bacteria (LAB) have been studied extensively for this purpose. However, when assessing the results comprehensively and reviewing the practicality and ethics of use, risks are evident, and concerns arise. In conclusion, our review suggests that there are too many issues with using LAB for aflatoxin binding for it to be safely promoted. Arguably, using binders in human food might even worsen food safety in the longer term.
  • Nowak, Jessika; Visnovsky, Sandra B.; Pitman, Andrew R.; Cruz, Cristina D.; Palmer, Jon; Fletcher, Graham C.; Flint, Steve (2021)
    Listeria monocytogenes is a ubiquitous foodborne pathogen that results in a high rate of mortality in sensitive and immunocompromised people. Contamination of food with L. monocytogenes is thought to occur during food processing, most often as a result of the pathogen producing a biofilm that persists in the environment and acting as the source for subsequent dispersal of cells onto food. A survey of seafoodprocessing plants in New Zealand identified the persistent strain 15G01, which has a high capacity to form biofilms. In this study, a transposon library of L. monocytogenes 15G01 was screened for mutants with altered biofilm formation, assessed by a crystal violet assay, to identify genes involved in biofilm formation. This screen identified 36 transposants that showed a significant change in biofilm formation compared to the wild type. The insertion sites were in 27 genes, 20 of which led to decreased biofilm formation and seven to an increase. Two insertions were in intergenic regions. Annotation of the genes suggested that they are involved in diverse cellular processes, including stress response, autolysis, transporter systems, and cell wall/membrane synthesis. Analysis of the biofilms produced by the transposants using scanning electron microscopy and fluorescence microscopy showed notable differences in the structure of the biofilms compared to the wild type. In particular, inactivation of uvrB and mltD produced coccoid-shaped cells and elongated cells in long chains, respectively, and the mgtB mutant produced a unique biofilm with a sandwich structure which was reversed to the wild-type level upon magnesium addition. The mltD transposant was successfully complemented with the wild-type gene, whereas the phenotypes were not or only partially restored for the remaining mutants. IMPORTANCE The major source of contamination of food with Listeria monocytogenes is thought to be due to biofilm formation and/or persistence in food-processing plants. By establishing as a biofilm, L. monocytogenes cells become harder to eradicate due to their increased resistance to environmental threats. Understanding the genes involved in biofilm formation and their influence on biofilm structure will help identify new ways to eliminate harmful biofilms in food processing environments. To date, multiple genes have been identified as being involved in biofilm formation by L. monocytogenes; however, the exact mechanism remains unclear. This study identified four genes associated with biofilm formation by a persistent strain. Extensive microscopic analysis illustrated the effect of the disruption of mgtB, clsA, uvrB, and mltD and the influence of magnesium on the biofilm structure. The results strongly suggest an involvement in biofilm formation for the four genes and provide a basis for further studies to analyze gene regulation to assess the specific role of these biofilm-associated genes.
  • Syvähuoko, Jenna (Helsingin yliopisto, 2015)
    The literature review focused on the chemical properties of Fusarium mycotoxins and their masked forms, analytical methods for their determination and the toxicological and legislative aspects. In the experimental study, a multi-method was developed and validated for the simultaneous quantification of several Fusarium toxins and their masked forms in barley, oats and wheat using liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. The simple “dilute-and-shoot” sample preparation procedure was applied, where the extraction was performed with a mixture of acetonitrile, water and acetic acid (79:20:1, v/v/v). Moreover, the aim was to obtain new data on the occurrence of the masked mycotoxins in barley, oats and wheat by analysing 95 cereal grain samples. The type A trichothecenes T-2 and HT-2 toxins (T-2 and HT-2) and the type B trichothecenes deoxynivalenol (DON) and nivalenol (NIV) as well as zearalenone (ZEN), together with 11 masked forms of them, were included based on their importance for the food safety in northern Europe. The analytes were separated on a reversed-phase column and detected in selected reaction monitoring (SRM) mode. Better peak shapes for the early eluting compounds and shorter analysis time were obtained with acetonitrile than methanol as the organic phase, thus it was chosen for the method. The method was validated according to the criteria set in the legislation. The limits of quantification varied from 0.3 to 15.9 ?g/kg. The recoveries were 92?115%, thus being within the tolerable ranges established in the legislation. The inter-day precisions (4?27%) were under the maximum permissible values. Therefore, the method proved to fit for the purpose. In this study, occurrence data on the masked mycotoxins in Finland were obtained for the first time. The presence of ZEN-16-glucoside (ZEN-16-G) and NIV-3-glucoside (NIV-3-G) were reported for the first time worldwide in some of the cereals. The most frequently found toxins were DON, NIV and HT-2. All of the masked mycotoxins included in the method were determined, the most common being DON-3-glucoside (DON-3-G), HT-2-glucoside (HT-2-G) and NIV-3-G.
  • Carlson, Mari (Helsingfors universitet, 2016)
    Economic integration refers to the theoretical background which is based on the functioning of regional trade agree-ments (RTAs). Trade in context of economic integration embodies special characteristics in comparison to classical free trade. The special characteristics are contested whether they are welfare enhancing or diverting. RTAs are trade agree-ments between two or more countries and their number has been increasing during the last decades. Such agreements play an important role in international agro-food trade as already over 50% of agricultural products are traded within or between RTAs. The increase in number of RTAs and wider inclusion of agricultural trade in these agreements have revealed new agricultural trade policy measures which distort trade in agro-food products. These are so called non-tariff measures of which this study focuses on sanitary and phytosanitary (SPS) measures. The legitimate intention of such measures is to protect plant, animal and human health and prevent the spreading of harmful pathogens through international trade. This study attempted to create a theoretical framework for analysis of trade effects caused by SPS measures. The ef-fects were found to depend first of all on the burden of compliance and the nature of a SPS measure. Burden of com-pliance was divided into three dimensions of specific, uniform or universal measures according to whom the costs are due. For the nature of the SPS measures three categories were identified: cost-increasing, quantity-restricting and combining SPS measures. The developed theoretical framework was applied to analyze the case of poultry meat trade between the EU and the US in a case where the SPS measure becomes ineffective. The SPS measure of pathogen reduction treatments (PRTs) applied by the EU was identified as a combining measure. After having analyzed the trade effects in partial equilibrium framework, the changes in economic welfare for the EU poultry meat market were quanti-fied. The quantification of the economic welfare measures was made by using partial equilibrium comparative static analysis combined with Marshallian economic surplus framework. Economic surplus measures were calculated by comparing the initial welfare levels with the corresponding levels after the policy change. The analysis concentrated on short-term effects and the base year used was 2013. The calculations proceeded by defining supply and demand equations to calculate equilibrium price and quantity in the present policy regime which enabled calculations of consumer and pro-ducer surpluses. Then, the new trade policy regime was introduced by manipulating producer price. Equations defined in the first stage were used to calculate new quantities for production and consumption in the EU. Then, consumer and producer surpluses were calculated in the new trade policy regime. Finally the obtained results were compared with each other. The results of the welfare analysis show that the SPS measure concerning the use of PRTs in poultry meat has impact on producer and consumer welfare in the EU. Consumer welfare increased after the SPS measure became ineffective. The explanation is the decrease in price which lead to increase in consumption. However, producer welfare decreased as a consequence of lower price. The production of poultry meat decreased which meant that the gap between the EU production and consumption increased. This indicated that the import demand for poultry meat increased for the EU. If the imports were not restricted from the US, consumers would be able to obtain the higher welfare level than before the change in policy regime.
  • Finnish Food Authority (Finnish Food Authority, 2019)
    Finnish Food Authority publications 5/2019
    This report presents for the year 2018 the results of regulatory control related to food safety, official controls and monitoring programmes on food and feed, as well as research and risk assessments. The report also assesses, based on the results, the status of food safety and future needs for regulatory activities in Finland. The report extends the annual report referred to in EU Control Regulation (EC) No. 882/2004 with respect to food safety where the annual report describes the results of control in the various sectors of the food supply chain as a whole. The results of regulatory control and research in 2018 demonstrate a good status of food safety in Finland. Domestically produced food does not contain chemical substances in levels that would be dangerous to the consumer. Foodstuffs tested contain food-poisoning causing bacteria in very low concentrations. The number of food-borne epidemics as well as the number of people affected increased notably from the previous year. The reason for this increase was mainly due to illnesses caused by noroviruses. The number of food frauds is increasing and fraudulent activities are also found in Finland. The number of food withdrawals is still increasing. As a rule, food sector companies operating in Finland meet food safety requirements excellently or very well. Severe shortcomings occur in very low numbers.
  • Finnish Food Authority (Finnish Food Authority, 2020)
    Finnish Food Authority publications 4/2020
    This report presents for the year 2019 the results of regulatory control related to food safety, official controls and monitoring programmes on food and feed, as well as research and risk assessments. The report also assesses, based on the results, the status of food safety and future needs for regulatory activities in Finland. The report extends the annual report referred to in the EU Control Regulation (EC) No. 882/2004, starting from 14.12.2019 the Official Controls Regulation (EU) 2017/625, with respect to food safety where the annual report describes the results of control in the various sectors of the food supply chain as a whole. The results of regulatory control and research in 2019 demonstrate a good status of food safety in Finland. Domestically produced food does not contain chemical substances in levels that would be dangerous to the consumer. Foodstuffs tested contain food-poisoning causing bacteria in very low concentrations. The number of food-borne epidemics as well as the number of people affected has decreased from the previous year. The amount of epidemics as well as the number of people affected varies significantly from year to year. The main pathogen in 2019 was still the norovirus. It spreads easily with the affected and often causes disease in large groups of people. The number of food frauds is increasing and fraudulent activities are also found in Finland. The number of food withdrawals is still increasing. As a rule, food sector companies operating in Finland meet food safety requirements excellently or very well. Severe shortcomings occur in very low numbers.
  • Finnish Food Authority (Finnish Food Authority, 2021)
    Finnish Food Authority publications 5/2021
    This report presents the 2020 results of regulatory control related to food safety, official controls and monitoring programmes on food and feed as well as research and risk assessments. The report also assesses, based on the results, the status of food safety and future needs for regulatory activities in Finland. The report extends the annual report referred to in the EU Control Regulation (EU) No. 2017/625 on official controls with respect to food safety; the annual report describes the results of the control in the various sectors of the food supply chain as a whole. The results of official controls and investigations from 2020 show that food safety is at a good level in Finland despite the COVID-19 pandemic. Domestic products do not contain such quantities of chemical substances that would be hazardous for the consumer and the level of food poisoning bacteria in the food studied is very low. In 2020 the number of food-borne epidemics was significantly lower than in previous years. For the first time the fight against crime in the food chain was incorporated into the national strategy and action plan for combating grey economy and economic crime for 2020–2023. The control activities planned by the food control authorities were mainly achieved. Despite the COVID-19 pandemic and restrictions and limitations the inspections, sampling and research could be carried out almost as planned. Remote inspections were introduced and controls were made to be more risk-based. The number of food recalls has increased dramatically for both domestic, internal market and third country products. Recalls are an indication of the effectiveness and responsibility of both official controls as well as own-check activities practised by companies.
  • Castro, Hanna; Jaakkonen, Anniina; Hakakorpi, Anna; Hakkinen, Marjaana; Isidro, Joana; Korkeala, Hannu; Lindström, Miia; Hallanvuo, Saija (2019)
    Packaged raw milk contaminated with Yersinia pseudotuberculosis mediated a large yersiniosis outbreak in southern Finland in 2014. The outbreak was traced back to a single dairy farm in southern Finland. Here we explore risk factors leading to the outbreak through epidemiologic investigation of the outbreak farm and through genomic and phenotypic characterization of the farm's outbreak and non-outbreak associated Y. pseudotuberculosis strains. We show that the outbreak strain persisted on the farm throughout the 7-month study, whereas the non-outbreak strains occurred sporadically. Phylogenomic analysis illustrated that the outbreak strain was related to previously published genomes of wild animal isolates from Finland, implying that wild animals were a potential source of the outbreak strain to the farm. We observed allelic differences between the farm's outbreak and non-outbreak strains in several genes associated with virulence, stress response and biofilm formation, and found that the outbreak strain formed biofilm in vitro and maintained better growth fitness during cold stress than the non-outbreak strains. Finally, we demonstrate the rapid growth of the outbreak strain in packaged raw milk during refrigerated storage. This study provides insight of the risk factors leading to the Y. pseudotuberculosis outbreak, highlights the importance of pest control to avoid the spread of pathogens from wild to domestic animals, and demonstrates that the cold chain is insufficient as the sole risk management strategy to control Y. pseudotuberculosis risk associated with raw drinking milk.
  • Castro, H.; Jaakkonen, A.; Hakakorpi, A.; Hakkinen, M.; Isidro, J.; Korkeala, H.; Lindström, M.; Hallanvuo, S. (2019)
    Frontiers in Microbiology Vol. 14, No. 10, p. 1049.
    Packaged raw milk contaminated with Yersinia pseudotuberculosis mediated a large yersiniosis outbreak in southern Finland in 2014. The outbreak was traced back to a single dairy farm in southern Finland. Here we explore risk factors leading to the outbreak through epidemiologic investigation of the outbreak farm and through genomic and phenotypic characterization of the farm’s outbreak and non-outbreak associated Y. pseudotuberculosis strains. We show that the outbreak strain persisted on the farm throughout the 7-month study, whereas the non-outbreak strains occurred sporadically. Phylogenomic analysis illustrated that the outbreak strain was related to previously published genomes of wild animal isolates from Finland, implying that wild animals were a potential source of the outbreak strain to the farm. We observed allelic differences between the farm’s outbreak and non-outbreak strains in several genes associated with virulence, stress response and biofilm formation, and found that the outbreak strain formed biofilm in vitro and maintained better growth fitness during cold stress than the non-outbreak strains. Finally, we demonstrate the rapid growth of the outbreak strain in packaged raw milk during refrigerated storage. This study provides insight of the risk factors leading to the Y. pseudotuberculosis outbreak, highlights the importance of pest control to avoid the spread of pathogens from wild to domestic animals, and demonstrates that the cold chain is insufficient as the sole risk management strategy to control Y. pseudotuberculosis risk associated with raw drinking milk.
  • Llarena, Ann-Katrin; Kivistö, Rauni (2020)
    Campylobacter jejuni (C. jejuni) is the most common cause of human bacterial gastroenteritis in the world. Food-borne campylobacteriosis is thought to be commonly caused by the handling and consumption of undercooked chicken meat, but the epidemiology of this disease is complex and remains poorly characterized, especially in the Nordic countries. Here, we used state-of-the-art methods in genetic epidemiology combined with patient background and temporal association data to trace domestically acquired human C. jejuni infections (n = 50) to chicken meat, in a midsize Nordic town in Finland during a seasonal peak. Although 59.2% of the human isolates shared a sequence type (ST) with a chicken batch slaughtered prior to the onset of disease, further analysis at the whole-genome level (core genome and whole-genome multilocus sequence typing, cgMLST and wgMLST, respectively) traced a mere nine cases (18.4%) to fresh chicken meat. Human isolates also shared genotypes with isolates collected from chicken batches slaughtered after the onset of the human disease, highlighting the role of alternative transmission pathways from chickens to humans besides the food chain, or a shared third source. The high resolution offered by wgMLST, combined with simple metadata, offers a more accurate way to trace sporadic cases to possible sources and reveal disseminated outbreak clustering in time, confirming the importance of complementing epidemiological investigations with molecular epidemiological data.
  • Nowak, J.; Visnovsky, S. B.; Cruz, C. D.; Fletcher, G. C.; van Vliet, A. H. M.; Hedderley, D.; Butler, R.; Flint, S.; Palmer, J.; Pitman, A. R. (2021)
    Aims To understand the genetics involved in surface attachment and biofilm formation ofListeria monocytogenes. Methods and Results Anin vitroscreen of a Himar1 transposon library ofL. monocytogenesstrain 15G01 identified three transposants that produced significantly different biofilm levels when compared to the wild-type strain; two mutants exhibited enhanced biofilm formation and one produced less biofilm biomass than the wild-type. The mutant 15G01mprF::Himar1, which had a transposon insertion in themprFgene, was selected for further analysis. The mutant produced a more densely populated biofilm on solid surfaces such as stainless steel and polystyrene, as determined using scanning electron and light microscopy. The 15G01mprF::Himar1 mutant remained viable in biofilms, but showed an increase in sensitivity to the cationic antimicrobial gallidermin. The mutant also displayed reduced invasiveness in CaCo-2 intestinal cells, suggesting virulence properties are compromised by the inactivation ofmprF. Conclusions Biofilm formation and gallidermin resistance ofL. monocytogenesis influenced bymprF, but this trait is associated with a compromise in invasiveness. Significance and Impact of the Study The presence of pathogenic microorganisms in the food processing environment can cause a significant problem, especially when these microorganisms are established as biofilms. This study shows that the inactivation of themprFgene results in enhanced biofilm formation and abiotic surface attachment ofL. monocytogenes.
  • Castro, Hanna; Douillard, Francois; Korkeala, Hannu; Lindström, Miia (2021)
    Listeria monocytogenes is a foodborne pathogen and a resilient environmental saprophyte. Dairy farms are a reservoir of L. monocytogenes, and strains can persist on farms for years. Here, we sequenced the genomes of 250 L. monocytogenes isolates to investigate the persistence and mobile genetic elements (MGEs) of Listeria strains inhabiting dairy farms. We performed a single-nucleotide polymorphism (SNP)-based phylogenomic analysis to identify 14 monophyletic clades of L. monocytogenes persistent on the farms for ≥6 months. We found that prophages and other mobile genetic elements were, on average, more numerous among isolates in persistent than nonpersistent clades, and we demonstrated that resistance genes against bacitracin, arsenic, and cadmium were significantly more prevalent among isolates in persistent than nonpersistent clades. We identified a diversity of mobile elements among the 250 farm isolates, including three novel plasmids, three novel transposons, and a novel prophage harboring cadmium resistance genes. Several of the mobile elements we identified in Listeria were identical to the mobile elements of enterococci, which is indicative of recent transfer between these genera. Through a genome-wide association study, we discovered that three putative defense systems against invading prophages and plasmids were negatively associated with persistence on farms. Our findings suggest that mobile elements support the persistence of L. monocytogenes on dairy farms and that L. monocytogenes inhabiting the agroecosystem is a potential reservoir of mobile elements that may spread to the food industry. IMPORTANCE Animal-derived raw materials are an important source of L. monocytogenes in the food industry. Knowledge of the factors contributing to the pathogen's transmission and persistence on farms is essential for designing effective strategies against the spread of the pathogen from farm to fork. An increasing body of evidence suggests that mobile genetic elements support the adaptation and persistence of L. monocytogenes in the food industry, as these elements contribute to the dissemination of genes encoding favorable phenotypes, such as resilience against biocides. Understanding of the role of farms as a potential reservoir of these elements is needed for managing the transmission of mobile elements across the food chain. Because L. monocytogenes coinhabits the farm ecosystem with a diversity of other bacterial species, it is important to assess the degree to which genetic elements are exchanged between Listeria and other species, as such exchanges may contribute to the rise of novel resistance phenotypes.
  • Matthew Omoruyi, Iyekhoetin; Hokkanen, Mirja; Pohjanvirta, Raimo (2020)
    Commercially processed meat and fish products are common sources of human exposure to chemical food mutagens. In this study, we investigated the mutagenic potential of 20 different commercially processed meat and fish products (7 product types with 2-3 lots of each), along with the presence of four principal polycyclic aromatic hydrocarbons (PAHs) (benzo[a]pyrene [BaP], benzo[b]fluoranthene [BbF], benzo[a]anthracene [BaA] and chrysene [CHR]) in them. Sample extraction was carried out by an accelerated solvent extraction method, while the concentrations of the 4 PAHs were determined by gas chromatography-tandem mass spectrometry (GC-MS/MS). The mutagenic potential of food extracts was assessed by the standard plate incorporation assay (Ames test) using two strains ofSalmonellatyphimurium (TA 100 and TA 98) both in the presence and the absence of metabolic activation (S9-mix). The results show that in the majority of food items investigated, PAH levels were below the limit of quantification (0.78 mu g/kg), except for smoked fish (0.8-15 mu g/kg for the 3 lots), one batch of which even exceeded the maximum limits for both the sum of the 4 PAHs (44 mu g/kg vs. 30 mu g/kg) and BaP (8.2 mu g/kg vs. 5.0 mu g/kg). Furthermore, all three batches of smoked fish were also found to be mutagenic on both strains ofSalmonella, both in the presence and the absence of metabolic activation. Overall, the data from both assays were in a fairly good agreement with one another, suggesting that PAHs are major contributors to mutagenicity of processed food products and the set maximum levels for PAHs are usually protective against food mutagenicity, although food samples harboring PAHs at levels approaching the maximum limits may exhibit mutagenic potential. Since the number of samples investigated was relatively small, further studies are warranted to verify the conclusions.
  • Rasimus-Sahari, Stiina; Mikkola, Raimo Olavi; Andersson, Aino Maria Alice; Jestoi, Marika; Salkinoja-Salonen, Mirja Sinikka (2015)
    Reasons for mammalian cell toxicity observed in barley and spring wheat grains were sought. Streptomyces sp. isolates from wheat and barley produced heat-stable methanol-soluble substances which inhibited the motility of exposed porcine spermatozoa used as a toxicity indicator. Several barley isolates produced antimycin A (2 to 5 ng/mg wet wt of biomass), a macrolide antibiotic known to block oxygen utilization in mitochondria. The antimycinproducing isolates were members of the Streptomyces albidoflavus group. In in vitro assays with porcine kidney tubular epithelial cells, the specific toxicity of antimycin A towards mitochondria was higher than that of the mycotoxin enniatin B but lower than that of the mitochondriotoxins cereulide and paenilide, produced by food-related Bacillus cereus and Paenibacillus tundrae, respectively. The toxic wheat isolates, related to Streptomyces sedi, did not produce antimycin A and or any other known toxin. Our results suggest that the presence of toxin-producing streptomycetes in stored cereal grains may pose a thus far unrecognized threat for food and feed safety.
  • Leon-Velarde, Carlos G.; Jun, Jin Woo; Skurnik, Mikael (2019)
    One of the human- and animal-pathogenic species in genus Yersinia is Yersinia enterocolitica, a food-borne zoonotic pathogen that causes enteric infections, mesenteric lymphadenitis, and sometimes sequelae such as reactive arthritis and erythema nodosum. Y. enterocolitica is able to proliferate at 4 degrees C, making it dangerous if contaminated food products are stored under refrigeration. The most common source of Y. enterocolitica is raw pork meat. Microbiological detection of the bacteria from food products is hampered by its slow growth rate as other bacteria overgrow it. Bacteriophages can be exploited in several ways to increase food safety with regards to contamination by Y. enterocolitica. For example, Yersinia phages could be useful in keeping the contamination of food products under control, or, alternatively, the specificity of the phages could be exploited in developing rapid and sensitive diagnostic tools for the identification of the bacteria in food products. In this review, we will discuss the present state of the research on these topics.