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Martin Wiedmann - One of the best experts on this subject based on the ideXlab platform.
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persistent listeria monocytogenes subtypes isolated from a Smoked Fish processing facility included both phage susceptible and resistant isolates
Food Microbiology, 2013Co-Authors: Kitiya Vongkamjan, Sherry Roof, Matthew J Stasiewicz, Martin WiedmannAbstract:Contamination of Ready-To-Eat foods with Listeria monocytogenes can typically be traced back to post-processing contamination from environmental sources; contamination is often linked to subtypes that persist in food associated environments. Although phage-based biocontrol strategies have been proposed for controlling this pathogen, information on the efficacy of phage treatment against diverse L. monocytogenes subtypes from food associated environments is still limited. We identified subtypes that were repeatedly found ("persistent") in a Smoked Fish processing facility by using EcoRI ribotyping data for isolates obtained in 1998-2009. PFGE analysis of 141 isolates (9 ribotypes) supported persistence for up to 11 years. Characterization of selected isolates, representing persistent subtypes, against a panel of 28 listeriaphages showed a wide range of likelihood of phage susceptibility, ranging from 4.6% (for 7 ribotype DUP-1043A isolates) to 95.4% (for 7 ribotype DUP-1044A isolates). In challenge studies with 10(5) and 10(6) CFU/ml L. monocytogenes, using phage cocktails and a commercial phage product at different phage-host ratios, one isolate (ribotype DUP-1043A) was not affected by any treatment. A reduction in L. monocytogenes counts of up to 4 log units was observed, after 8 h of treatment, in isolates of two ribotypes, but subsequent re-growth occurred. Survivor isolates obtained after 24 h of treatment showed decreased susceptibility to individual phages included in the phage cocktail, suggesting rapid emergence of resistant subtypes.
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tracking of listeria monocytogenes in Smoked Fish processing plants
Journal of Food Protection, 2004Co-Authors: Joanne Thimothe, Kenneth L Gall, Kendra K Nightingale, Virginia N Scott, Martin WiedmannAbstract:Four Smoked Fish processing plants were used as a model system to characterize Listeria monocytogenes contamination patterns in ready-to-eat food production environments. Each of the four plants was sampled monthly for approximately 1 year. At each sampling, four to six raw Fish and four to six finished product samples were collected from corresponding lots. In addition, 12 to 14 environmental sponge samples were collected several hours after the start of production at sites selected as being likely contamination sources. A total of 234 raw Fish, 233 finished products, and 553 environmental samples were tested. Presumptive Listeria spp. were isolated from 16.7% of the raw Fish samples, 9.0% of the finished product samples, and 27.3% of the environmental samples. L. monocytogenes was isolated from 3.8% of the raw Fish samples (0 to 10%, depending on the plant), 1.3% of the finished product samples (0 to 3.3%), and 12.8% of the environmental samples (0 to 29.8%). Among the environmental samples, L. monocytogenes was found in 23.7% of the samples taken from drains, 4.8% of the samples taken from food contact surfaces, 10.4% of the samples taken from employee contact surfaces (aprons, hands, and door handles), and 12.3% of the samples taken from other nonfood contact surfaces. Listeria spp. were isolated from environmental samples in each of the four plants, whereas L. monocytogenes was not found in any of the environmental samples from one plant. Overall, the L. monocytogenes prevalence in the plant environment showed a statistically significant (P < 0.0001) positive relationship with the prevalence of this organism in finished product samples. Automated EcoRI ribotyping differentiated 15 ribotypes among the 83 L. monocytogenes isolates. For each of the three plants with L. monocytogenes-positive environmental samples, one or two ribotypes seemed to persist in the plant environment during the study period. In one plant, a specific L. monocytogenes ribotype represented 44% of the L. monocytogenes-positive environmental samples and was also responsible for one of the two finished product positives found in this plant. In another plant, a specific L. monocytogenes ribotype persisted in the raw Fish handling area. However, this ribotype was never isolated from the finished product area in this plant, indicating that this operation has achieved effective separation of raw and finished product areas. Molecular subtyping methods can help identify plant-specific L. monocytogenes contamination routes and thus provide the knowledge needed to implement improved L. monocytogenes control strategies.
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listeria monocytogenes contamination patterns for the Smoked Fish processing environment and for raw Fish
Journal of Food Protection, 2003Co-Authors: Adam D Hoffman, Kenneth L Gall, Dawn M Norton, Martin WiedmannAbstract:Reliable data on the sources of Listeria monocytogenes contamination in cold-Smoked Fish processing are crucial in designing effective intervention strategies. Environmental samples (n = 512) and raw Fish samples (n = 315) from two Smoked Fish processing facilities were screened for L. monocytogenes, and all isolates were subtyped by automated ribotyping to examine the relationship between L. monocytogenes contamination from raw materials and that from environmental sites. Samples were collected over two 8-week periods in early spring and summer. The five types of raw Fish tested included lake whiteFish, sableFish, farm-raised Norwegian salmon, farm-raised Chilean salmon, and feral (wild-caught) salmon from the U.S. West Coast. One hundred fifteen environmental samples and 46 raw Fish samples tested positive for L. monocytogenes. Prevalence values for environmental samples varied significantly (P < 0.0001) between the two plants; plant A had a prevalence value of 43.8% (112 of 256 samples), and plant B ha...
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molecular studies on the ecology of listeria monocytogenes in the Smoked Fish processing industry
Applied and Environmental Microbiology, 2001Co-Authors: Dawn M Norton, Kenneth L Gall, Meghan Mccamey, Janet M Scarlett, Kathryn J Boor, Martin WiedmannAbstract:We have applied molecular approaches, including PCR-based detection strategies and DNA fingerprinting methods, to study the ecology of Listeria monocytogenes in food processing environments. A total of 531 samples, including raw Fish, Fish during the cold-smoking process, finished product, and environmental samples, were collected from three Smoked Fish processing facilities during five visits to each facility. A total of 95 (17.9%) of the samples tested positive for L. monocytogenes using a commercial PCR system (BAX for Screening/Listeria monocytogenes), including 57 (27.7%) environmental samples (n = 206), 8 (7.8%) raw material samples (n = 102), 23 (18.1%) samples from Fish in various stages of processing(n = 127), and 7 (7.3%) finished product samples (n = 96). L. monocytogenes was isolated from 85 samples (16.0%) using culture methods. Used in conjunction with a 48-h enrichment in Listeria Enrichment Broth, the PCR system had a sensitivity of 91.8% and a specificity of 96.2%. To track the origin and spread of L. monocytogenes, isolates were fingerprinted by automated ribotyping. Fifteen different ribotypes were identified among 85 isolates tested. Ribotyping data established possible contamination patterns, implicating raw materials and the processing environment as potential sources of finished product contamination. Analysis of the distribution of ribotypes revealed that each processing facility had a unique contamination pattern and that specific ribotypes persisted in the environments of two facilities over time (P ≤ 0.0006). We conclude that application of molecular approaches can provide critical information on the ecology of different L. monocytogenes strains in food processing environments. This information can be used to develop practical recommendations for improved control of this important food-borne pathogen in the food industry.
Florentina Israelroming - One of the best experts on this subject based on the ideXlab platform.
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quantification and risk assessment of carcinogenic polycyclic aromatic hydrocarbons in retail Smoked Fish and Smoked cheeses
Food Control, 2021Co-Authors: Radu C Racovita, Catinca Secuianu, Florentina IsraelromingAbstract:Abstract Polycyclic aromatic hydrocarbons (PAHs) are known or potential carcinogens occurring in foodstuffs during smoking processes, among others. The European Commission (EC) has defined clear limits for benzo[a]pyrene and the total concentration of benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo [a]pyrene – known as the PAH4 group – that must not be exceeded by any food product commercialized within the European Union (EC Regulation No. 835/2011). In this work, we determined the concentrations of 16 PAHs, including the PAH4 group, in 17 retail Smoked Fish and 11 retail Smoked cheeses from four and nine producers, respectively. To this end, we first developed a gas chromatography-mass spectrometry method for identification and quantification of PAHs in Smoked food matrices and validated it intra-laboratory according to the guidelines of EC Regulation No. 836/2011. For the extraction of PAHs from foodstuffs and their further clean-up, we adopted a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) protocol, based on partitioning between acetonitrile and water, followed by dispersive solid-phase extraction using commercially available QuEChERS kits. The analyses of Smoked Fish revealed a fairly wide range of PAH concentrations, resulting both from differences in the type of Smoked Fish and different producers. Smoked sprat exhibited the highest total PAH concentration (around 100 ng/g), with acenaphthylene, phenanthrene, and fluorene contributing more than half of this amount, while the lowest PAH content (about 30 ng/g) was observed in Smoked trout. None of the analyzed Fish samples exceeded the EC limits for either benzo [a]pyrene or PAH4 in the corresponding product categories. While no such limits exist for the Smoked cheese category, it was found Smoked cheeses had much lower PAH levels compared to Smoked Fish, around 10 ng/g for ordinary pressed cheeses and 20 ng/g for generically designated “Bradet” cheeses, irrespective of producer. The majority PAHs in all investigated cheeses were found to be phenanthrene, naphthalene, and fluorene, while PAH4 accounted for only about 10% of total PAHs. Cancer risk assessment was performed using both margin of exposure and incremental lifetime cancer risk parameter determinations and none of the samples analyzed showed significant concern.
Lawrence Ikechukwu Ezemonye - One of the best experts on this subject based on the ideXlab platform.
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human health risk assessment of polycyclic aromatic hydrocarbons pahs in Smoked Fish species from markets in southern nigeria
Toxicology reports, 2017Co-Authors: Isioma Tongo, Ozekeke Ogbeide, Lawrence Ikechukwu EzemonyeAbstract:Polycyclic Aromatic Hydrocarbons (PAHs) levels in four commonly consumed Smoked Fish species from markets in Southern Nigeria were assessed to evaluate possible human health risks associated with consumption. Varying levels of PAH congeners were observed in the Fish tissues with the highest total concentration of PAHs in Scomber scombrus. High concentrations of benzo(a)pyrene was observed in Clarias gariepinus and Ethmalosa fimbriata with values above the guideline value of 0.05 mg/kg. The Dietary Daily Intake (DDI) value for total PAHs (∑PAHs) was highest for S. scombrus while the DDI value for the total carcinogenic PAHs (∑CPAHs) was highest for E. fimbriata. Carcinogenic human health risk assessment using carcinogenic toxic equivalents (TEQ), indicated that consumption of E. fimbriata has a higher potential to cause carcinogenic risks. TEQ values for all the Fish species were however, below the estimated screening value (SV) of 3.556 mg/kg, while the estimated cumulative excess cancer risk (ECR) for E. fimbriata and C. gariepinus and PAH4 index for all the assessed Fish species exceeded threshold values indicating potential carcinogenic risk from consumption.
Parivash Haratian - One of the best experts on this subject based on the ideXlab platform.
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microwave assisted extraction and dispersive liquid liquid microextraction followed by gas chromatography mass spectrometry for isolation and determination of polycyclic aromatic hydrocarbons in Smoked Fish
Journal of Chromatography A, 2012Co-Authors: Vahid Ghasemzadehmohammadi, Abdorreza Mohammadi, Maryam Hashemi, Ramin Khaksar, Parivash HaratianAbstract:Abstract A simple and efficient method was developed using microwave-assisted extraction (MAE) and dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–mass spectrometry (GC–MS) for the extraction and quantification of 16 polycyclic aromatic hydrocarbons (PAHs) in Smoked Fish. Benzo[a]pyrene, chrysene and pyrene were employed as model compounds and spiked to Smoked Fish to assess the extraction procedure. Several parameters, including the nature and volume of hydrolysis, extracting and disperser solvents, microwave time and pH, were optimized. In the optimum condition for MAE, 1 g of Fish sample was extracted in 12 mL KOH (2 M) and ethanol with a 50:50 ratio in a closed-vessel system. For DLLME, 500 μL of acetone (disperser solvent) containing 100 μL of ethylene tetrachloride (extraction solvent) was rapidly injected by syringe into 12 mL of the sample extract solution (previously adjusted to pH 6.5), thereby forming a cloudy solution. Phase separation was performed by centrifugation and a volume of 1.5 μL of the sedimented phase was analyzed by GC–MS in select ion monitoring (SIM) mode. Satisfactory results were achieved when this method was applied to analyze the PAHs in Smoked Fish samples. The MAE–DLLME method coupled with GC–MS provided excellent enrichment factors (in the range of 244–373 for 16 PAHs) and good repeatability (with a relative standard deviation between 2.8 and 9%) for spiked Smoked Fish. The calibration graphs were linear in the range of 1–200 ng g−1, with the square of the correlation coefficient (R2) > 0.981 and detection limits between 0.11 and 0.43 ng g−1. The recoveries of those compounds in Smoked Fish were from 82.1% to 105.5%. A comparison of this method with previous methods demonstrated that the proposed method is an accurate, rapid and reliable sample-pretreatment method that gives very good enrichment factors and detection limits for extracting and determining PAHs from Smoked Fish.
G. Dureke - One of the best experts on this subject based on the ideXlab platform.
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Microbiology, heterocyclic amines and polycyclic aromatic hydrocarbons profiles of some grilled, roasted and Smoked foods in Lagos and Ogun States, Nigeria
African Journal of Food Science, 2018Co-Authors: Solomon U. Oranusi, E. A. Onibokun, Yemisi Dorcas Obafemi, G. DurekeAbstract:Dietary intake of polycyclic aromatic hydrocarbons (PAH) and heterocyclic amines (HCA) has posted a great health risk as they have been identified as a most potent human carcinogen. Microbial quality of food is also of concern as they contribute to food poisoning and infection. Sixty food samples comprising roasted yam, plantain, grilled and Smoked Fish and meat were randomly sampled from Lagos and Ogun State, Nigeria, and the PAHs, HCAs contents and microbial load were determined. Isolates were subjected to antibiogram assay. The pH of the samples ranged between 5.08 and 7.49, titrable acidity was in the range of 0.50 and 1.20. Staphylococcus, Bacillus, Micrococcus, Proteus, Pseudomonas, Citrobacter and Klebsiella sp. had been identified. Antibiogram revealed that the isolates were multi-resistant and most resistant to ceftazidime, cloxacillin and tetracycline and more susceptible to ofloxacin. PAHs were detected in some grilled, roasted and Smoked samples and with the highest concentrations 314.85 and 139.97 μg/g Dibenzene[a,h]anthracene established in roasted yam and Smoked Fish samples. Only 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was detected in grilled Fish and meat samples. This study therefore established the presence of chemical and microbial contaminants in some of the food items investigated. It recommended that strict sanitary practices and appropriate cooking methods be enforced during food preparation.