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Jesús L. Romalde - One of the best experts on this subject based on the ideXlab platform.

  • Application of phage therapy during bivalve Depuration improves Escherichia coli decontamination
    Food Microbiology, 2017
    Co-Authors: Carla Pereira, Catarina Moreirinha, Maria L. Nunes, Luís Teles, Rui J M Rocha, Jesús L. Romalde, Ricardo Calado, Adelaide Almeida
    Abstract:

    The present study investigated the potential application of the bacteriophage (or phage) phT4A, ECA2 and the phage cocktail phT4A/ECA2 to decrease the concentration of Escherichia coli during the Depuration of natural and artificially contaminated cockles. Depuration in static seawater at multiplicity of infection (MOI) of 1 with single phage suspensions of phT4A and ECA2 was the best condition, as it decreased by ∼2.0 log CFU/g the concentration of E. coli in artificially contaminated cockles after a 4 h of treatment. When naturally contaminated cockles were treated in static seawater with single phage suspensions and the phage cocktail, similar decreases in the concentration of E. coli (∼0.7 log CFU/g) were achieved. However, when employing the phage cocktail, a longer treatment time was required to obtain comparable results to those achieved when using single phage suspensions. When naturally contaminated cockles were depurated with phage phT4A in a recirculated seawater system (mimicking industrial Depuration conditions), a 0.6 log CFU/g reduction of E. coli was achieved after a 2 h of treatment. When the Depuration process was performed without phage addition, a 4 h treatment was necessary to obtain a similar decrease. By combining phage therapy and Depuration procedures, a reduction in bivalves Depuration period can be achieved for, thus decreasing the cost associated with this procedure and even enhance the quality and safety of depurated bivalves destined for human consumption.

  • Mathematical model for viral Depuration kinetics in shellfish: an useful tool to estimate the risk for the consumers.
    Food Microbiology, 2015
    Co-Authors: David Polo, Xabier Feal, Jesús L. Romalde
    Abstract:

    Abstract Enteric virus Depuration from shellfish is a complex biological process that may be influenced by biological properties of the mollusc and/or virus species. On the basis of previous experimental data, a mathematical model was developed to characterize the kinetics of viral elimination during the Depuration process. The experimental data consisted on twenty Depuration trials, each with 60 kg of Manila clams (Venerupis philippinarum ) and mediterranean mussels (Mytilus galloprovincialis) previously subjected to bioaccumulation with HAV or MNV-1 (as a surrogate for human norovirus), that were performed in an experimental Depuration system during 7 days. It was observed that although viral loads decay along Depuration, a residual viral load remains at the end of the process suggesting a decomposition of viral load in a diluted load (susceptible of Depuration) and a non-diluted load (unavailable to depurate). The model yielded a general equation, which can predict the viral load at any Depuration time knowing the specific filtration rate, dependent on the bivalve species, and specific viral properties. The mathematical model can be combined with quantitative risk assessment calculations to determine the safety of the depurated shellfish, which can be very helpful not only for shellfish producers but also to public health authorities.

  • Effectiveness of Depuration for hepatitis A virus removal from mussels (Mytilus galloprovincialis).
    International journal of food microbiology, 2014
    Co-Authors: David Polo, Cristina Álvarez, Ángeles Longa, Jesús L. Romalde
    Abstract:

    Abstract The efficacy and kinetic of Depuration of hepatitis A virus (HAV) were evaluated under experimental conditions with Mediterranean mussels (Mytilus galloprovincialis) subjected previously to bioaccumulation processes. Seven independent trials (70 kg of mussels each) were performed in a closed experimental system using two different water temperatures (13 and 17 °C) during 7 days. The real time RT-PCR technique with TaqMan probes was used for viral quantification. Qualitative infectivity assays were conducted to test the presence of infectious viral particles at the end of the Depuration period. The Depuration trials showed an average reduction of HAV levels of aproximately 1.1 Log units (> 90%). However, the average final viral loads in shellfish samples remain at relatively high levels (6.5 × 103 RNA copies/g digestive tissue) and still infectious. A positive correlation between the initial and the final numbers of the viral RNA copies was observed. The reduction of HAV showed a two-phase removal kinetic, an initial logarithmic trendline, with a rapid reduction of viruses during the first 24–48 h of Depuration, and a subsequent stabilization with a slower Depuration rate until the end of the process.

  • Depuration kinetics of murine norovirus in shellfish.
    Food Research International, 2014
    Co-Authors: David Polo, Xabier Feal, Miguel F. Varela, Alba Monteagudo, Jesús L. Romalde
    Abstract:

    Abstract This study evaluates and compares the uptake rates and Depuration kinetics of murine norovirus (MNV-1), as a human norovirus surrogate, in Manila clams ( Venerupis philippinarum ) and Mediterranean mussels ( Mytilus galloprovincialis ). Ten trials of 70 kg/trial (five with each mollusk) were performed. Mollusks were subjected to a controlled bioaccumulation step of 24 h with 10 2  pfu MNV-1/mL seawater. Then, mollusks were relocated in an experimental Depuration system for 7 days. Viral contamination was quantified after bioaccumulation and then daily during Depuration by reverse transcription-real time PCR (RT-qPCR) with TaqMan probes. Infectivity assays were conducted to test the presence of infectious viral particles at the end of the Depuration period. Results showed significant differences in the uptake and removal viral rates between molluscan species. The average viral uptake for clams and mussels were 5.4 × 10 6 and 4.0 × 10 5  RNA copies/g digestive tissue respectively, representing an uptake rate > 90% higher in clams. The average reductions with regard to the initial levels were 60.5% for clams and 91.6% for mussels. On the other hand, a similar logarithmic trend line in MNV-1 Depuration kinetics was observed in both bivalves, with two differentiated phases: an initial rapid reduction of viruses during the first 24–72 h of Depuration, and a subsequent stabilization with a slower Depuration rate. All trials with clams and mussels showed significant viral reductions but remaining virus were still infectious at the end of the process.

  • Viral elimination during commercial Depuration of shellfish
    Food Control, 2014
    Co-Authors: David Polo, Cristina Álvarez, Ángeles Longa, Jorge Díez, Susana Darriba, Jesús L. Romalde
    Abstract:

    The effectiveness of Depuration for the removal of hepatitis A virus (HAV), norovirus (NoV) genogroups I (GI) and II (GII), and F+RNA bacteriophage (F+RNA) was evaluated for pullet carpet shell clams (Venerupis pullastra) and Mediterranean mussels (Mytilus galloprovincialis). The objective was to compare the behaviour of the different pathogens under commercial Depuration conditions during 7 days in an authorized plant. Standard double agar overlay method (ISO 10705-1) was employed for F+RNA quantification. Recently developed ISO/TS 15216:2013 standard method, based on RT-real time PCR, were employed for the quantification of HAV and NoV. The reduction of F+RNA showed a two-phase Depuration kinetic. The average reduction rates were 1-log units for clams and 2-log units for mussels, with residual levels after the process of 6.3 × 103 and 8.3 × 101 F+RNA/100 g, respectively. HAV, NoV GI and GII were detected intermittently throughout the entire process, ranging mostly from 103 to 105 RNA copies/g digestive tissue (DT). NoV GI showed the higher viral levels followed by NoV GII and HAV. All of them were detected in clams after seven days of Depuration, however, in mussels only NoV GI was detected after the process. Generally, clams showed slower Depuration rates and higher contamination levels for all viruses analysed.

P Howgate - One of the best experts on this subject based on the ideXlab platform.

  • tainting of farmed fish by geosmin and 2 methyl iso borneol a review of sensory aspects and of uptake Depuration
    Aquaculture, 2004
    Co-Authors: P Howgate
    Abstract:

    Abstract The review is a critical appraisal of the literature on sensory properties of geosmin and 2-methyl-iso-borneol (MIB) as chemicals that induce taints in freshwater fish, discusses the perception of these chemicals in fish as taint, particularly quantitative aspects, and discusses the kinetics of the uptake and Depuration of the chemicals into/from fish. Reasonable values of detection thresholds of geosmin and MIB in water are 0.015 and 0.035 μg l−1, respectively. Their detection thresholds in fish are affected by the lipid content of the fish. The kinetics of uptake and Depuration of geosmin and MIB can be modelled very well by the one compartment kinetic model extensively used in studies of uptake of polluting chemicals. Geosmin and MIB contents in fish reduce exponentially with time in the Depuration phase, but intensity of taint is predicted to decline linearly with Depuration time. The implications for quality assurance and Depuration practices in aquaculture of the sensory properties of geosmin and MIB and of factors that affect the kinetics of uptake and Depuration are discussed.

  • Tainting of farmed fish by geosmin and 2-methyl-iso-borneol: a review of sensory aspects and of uptake/Depuration
    Aquaculture, 2003
    Co-Authors: P Howgate
    Abstract:

    Abstract The review is a critical appraisal of the literature on sensory properties of geosmin and 2-methyl-iso-borneol (MIB) as chemicals that induce taints in freshwater fish, discusses the perception of these chemicals in fish as taint, particularly quantitative aspects, and discusses the kinetics of the uptake and Depuration of the chemicals into/from fish. Reasonable values of detection thresholds of geosmin and MIB in water are 0.015 and 0.035 μg l−1, respectively. Their detection thresholds in fish are affected by the lipid content of the fish. The kinetics of uptake and Depuration of geosmin and MIB can be modelled very well by the one compartment kinetic model extensively used in studies of uptake of polluting chemicals. Geosmin and MIB contents in fish reduce exponentially with time in the Depuration phase, but intensity of taint is predicted to decline linearly with Depuration time. The implications for quality assurance and Depuration practices in aquaculture of the sensory properties of geosmin and MIB and of factors that affect the kinetics of uptake and Depuration are discussed.

David Polo - One of the best experts on this subject based on the ideXlab platform.

  • Depuration and Relaying: A Review on Potential Removal of Norovirus from Oysters
    Comprehensive Reviews in Food Science and Food Safety, 2017
    Co-Authors: Catherine Mcleod, Jean-claude Le Saux, David Polo, Françoise S. Le Guyader
    Abstract:

    Pollution of coastal waters can result in contamination of bivalve shellfish with human enteric viruses, including norovirus (NoV), and oysters are commonly implicated in outbreaks. Depuration is a postharvest treatment involving placement of shellfish in tanks of clean seawater to reduce contaminant levels; this review focuses on the efficacy of Depuration in reducing NoV in oysters. There have been many NoV outbreaks from depurated oysters containing around 103 genome copies/g oyster tissue, far exceeding the median infectious dose (ID50). Half of the published NoV reduction experiments showed no decrease in NoV during Depuration, and in the remaining studies it took between 9 and 45.5 d for a 1-log reduction—significantly longer than commercial Depuration time frames. Surrogate viruses are more rapidly depurated than NoV; the mean number of days to reduce NoV by 1 log is 19, and 7.5 d for surrogates. Thus, surrogates do not appear to be suitable for assessing virological safety of depurated oysters; data on reduction of NoV infectivity during Depuration would assist evaluations on surrogate viruses and the impact of methods used. The longer persistence of NoV highlights its special relationship with oysters, which involves the binding of NoV to histo-blood group-like ligands in various tissues. Given the persistence of NoV and on-going outbreaks, Depuration as currently performed appears ineffective in guaranteeing virologically safe oysters. Conversely, relaying oysters for 4 wk is more successful, with low NoV concentrations and no illnesses associated with products. The ineffectiveness of Depuration emphasizes the need for coastal water quality to be improved to ensure oysters are safe to eat.

  • Mathematical model for viral Depuration kinetics in shellfish: an useful tool to estimate the risk for the consumers.
    Food Microbiology, 2015
    Co-Authors: David Polo, Xabier Feal, Jesús L. Romalde
    Abstract:

    Abstract Enteric virus Depuration from shellfish is a complex biological process that may be influenced by biological properties of the mollusc and/or virus species. On the basis of previous experimental data, a mathematical model was developed to characterize the kinetics of viral elimination during the Depuration process. The experimental data consisted on twenty Depuration trials, each with 60 kg of Manila clams (Venerupis philippinarum ) and mediterranean mussels (Mytilus galloprovincialis) previously subjected to bioaccumulation with HAV or MNV-1 (as a surrogate for human norovirus), that were performed in an experimental Depuration system during 7 days. It was observed that although viral loads decay along Depuration, a residual viral load remains at the end of the process suggesting a decomposition of viral load in a diluted load (susceptible of Depuration) and a non-diluted load (unavailable to depurate). The model yielded a general equation, which can predict the viral load at any Depuration time knowing the specific filtration rate, dependent on the bivalve species, and specific viral properties. The mathematical model can be combined with quantitative risk assessment calculations to determine the safety of the depurated shellfish, which can be very helpful not only for shellfish producers but also to public health authorities.

  • Effectiveness of Depuration for hepatitis A virus removal from mussels (Mytilus galloprovincialis).
    International journal of food microbiology, 2014
    Co-Authors: David Polo, Cristina Álvarez, Ángeles Longa, Jesús L. Romalde
    Abstract:

    Abstract The efficacy and kinetic of Depuration of hepatitis A virus (HAV) were evaluated under experimental conditions with Mediterranean mussels (Mytilus galloprovincialis) subjected previously to bioaccumulation processes. Seven independent trials (70 kg of mussels each) were performed in a closed experimental system using two different water temperatures (13 and 17 °C) during 7 days. The real time RT-PCR technique with TaqMan probes was used for viral quantification. Qualitative infectivity assays were conducted to test the presence of infectious viral particles at the end of the Depuration period. The Depuration trials showed an average reduction of HAV levels of aproximately 1.1 Log units (> 90%). However, the average final viral loads in shellfish samples remain at relatively high levels (6.5 × 103 RNA copies/g digestive tissue) and still infectious. A positive correlation between the initial and the final numbers of the viral RNA copies was observed. The reduction of HAV showed a two-phase removal kinetic, an initial logarithmic trendline, with a rapid reduction of viruses during the first 24–48 h of Depuration, and a subsequent stabilization with a slower Depuration rate until the end of the process.

  • Depuration kinetics of murine norovirus in shellfish.
    Food Research International, 2014
    Co-Authors: David Polo, Xabier Feal, Miguel F. Varela, Alba Monteagudo, Jesús L. Romalde
    Abstract:

    Abstract This study evaluates and compares the uptake rates and Depuration kinetics of murine norovirus (MNV-1), as a human norovirus surrogate, in Manila clams ( Venerupis philippinarum ) and Mediterranean mussels ( Mytilus galloprovincialis ). Ten trials of 70 kg/trial (five with each mollusk) were performed. Mollusks were subjected to a controlled bioaccumulation step of 24 h with 10 2  pfu MNV-1/mL seawater. Then, mollusks were relocated in an experimental Depuration system for 7 days. Viral contamination was quantified after bioaccumulation and then daily during Depuration by reverse transcription-real time PCR (RT-qPCR) with TaqMan probes. Infectivity assays were conducted to test the presence of infectious viral particles at the end of the Depuration period. Results showed significant differences in the uptake and removal viral rates between molluscan species. The average viral uptake for clams and mussels were 5.4 × 10 6 and 4.0 × 10 5  RNA copies/g digestive tissue respectively, representing an uptake rate > 90% higher in clams. The average reductions with regard to the initial levels were 60.5% for clams and 91.6% for mussels. On the other hand, a similar logarithmic trend line in MNV-1 Depuration kinetics was observed in both bivalves, with two differentiated phases: an initial rapid reduction of viruses during the first 24–72 h of Depuration, and a subsequent stabilization with a slower Depuration rate. All trials with clams and mussels showed significant viral reductions but remaining virus were still infectious at the end of the process.

  • Viral elimination during commercial Depuration of shellfish
    Food Control, 2014
    Co-Authors: David Polo, Cristina Álvarez, Ángeles Longa, Jorge Díez, Susana Darriba, Jesús L. Romalde
    Abstract:

    The effectiveness of Depuration for the removal of hepatitis A virus (HAV), norovirus (NoV) genogroups I (GI) and II (GII), and F+RNA bacteriophage (F+RNA) was evaluated for pullet carpet shell clams (Venerupis pullastra) and Mediterranean mussels (Mytilus galloprovincialis). The objective was to compare the behaviour of the different pathogens under commercial Depuration conditions during 7 days in an authorized plant. Standard double agar overlay method (ISO 10705-1) was employed for F+RNA quantification. Recently developed ISO/TS 15216:2013 standard method, based on RT-real time PCR, were employed for the quantification of HAV and NoV. The reduction of F+RNA showed a two-phase Depuration kinetic. The average reduction rates were 1-log units for clams and 2-log units for mussels, with residual levels after the process of 6.3 × 103 and 8.3 × 101 F+RNA/100 g, respectively. HAV, NoV GI and GII were detected intermittently throughout the entire process, ranging mostly from 103 to 105 RNA copies/g digestive tissue (DT). NoV GI showed the higher viral levels followed by NoV GII and HAV. All of them were detected in clams after seven days of Depuration, however, in mussels only NoV GI was detected after the process. Generally, clams showed slower Depuration rates and higher contamination levels for all viruses analysed.

Covadonga R. Arias - One of the best experts on this subject based on the ideXlab platform.

  • Effective reduction of Vibrio vulnificus in the Eastern oyster (Crassostrea virginica) using high salinity Depuration
    Food microbiology, 2012
    Co-Authors: Andrea M. Larsen, F. Scott Rikard, William C. Walton, Covadonga R. Arias
    Abstract:

    Depuration under different salinities was used to reduce the human pathogen Vibrio vulnificus from Eastern oysters (Crassostrea virginica). Individual recirculating systems were used to test the efficacy of Depuration at three salinities (15, 25, and 35 psu) in four independent trials during a 14 day period. Initial loads of V. vulnificus were higher than 10,000 MPN/g of oyster meat in all trials. Data showed that 25 and 35 psu treatments were more efficient in reducing V. vulnificus numbers than 15 psu with an overall reduction of >3 logs. A significant decrease in MPN/g was observed as early as day 6 and further reductions were observed at day 10, while longer Depurations did not improve efficacy. Only the highest salinity (35 psu) was capable of reducing V. vulnificus numbers to the FDA recommended level of

  • Evaluation of a flow-through Depuration system to eliminate the human pathogen Vibrio vulnificus from oysters.
    Journal of Aquaculture Research & Development, 2010
    Co-Authors: Matthew Robert Lewis, Scott Rikard, Covadonga R. Arias
    Abstract:

    The efficacy of a flow-through Depuration system in eliminating the human pathogen Vibrio vulnificus from eastern oysters ( Crassostrea virginica ) collected from the North Gulf of Mexico coast was evaluated in this study. Depuration experiments were conducted with artificially inoculated oysters using laboratory-grown strains of V. vulnificus as well as with naturally contaminated oysters. Determination of V. vulnificus numbers in oyster tissues was conducted at 0, 1, 2, 3 and 6 days of Depuration. Results showed that the Depuration of V vulnificus is possible using a flow-through system. Numbers of V. vulnificus in laboratory-inoculated oysters were reduced from >100,000 Most Probable Number (MPN)/g of oyster tissue to 23 MPN/g after six days of Depuration. As expected Depuration results of naturally contaminated oysters were more variable. Depuration at low temperature (15°C) had very little success in reducing the numbers of V. vulnificus in oyster tissues. On the contrary, when flow rate was increased from 11 L/m to 68 L/m, numbers of V. vulnificus in oysters were reduced from a starting concentration of 110,000 MPN/g to 3 MPN/g in six days. Nevertheless, a high-flow rate was not enough to eliminate V. vulnificus from oysters consistently. Vibrio vulnificus was effectively eliminated from oysters only when incoming water salinity was higher than 30 parts per thousand (ppt). Depuration did not select for pathogenic V. vulnificus strains. Pre- and post Depuration V. vulnificus isolates contained similar proportions of the proposed more virulent type.

Yicheng Su - One of the best experts on this subject based on the ideXlab platform.

  • temperature effects on the Depuration of vibrio parahaemolyticus and vibrio vulnificus from the american oyster crassostrea virginica
    Journal of Food Science, 2009
    Co-Authors: M J Chae, D Cheney, Yicheng Su
    Abstract:

    : This study investigated temperature effects on Depuration for reducing Vibrio parahaemolyticus and Vibrio vulnificus in American oyster (Crassostrea virginica). Raw oysters were inoculated with 5-strain cocktail of V. parahaemolyticus or V. vulnificus to levels of 10(4) to 10(5) MPN (most probable number)/g and depurated in artificial seawater (ASW) at 22, 15, 10, and 5 degrees C. Depuration of oysters at 22 degrees C had limited effects on reducing V. parahaemolyticus or V. vulnificus in the oysters. Populations of V. parahaemolyticus and V. vulnificus were reduced by 1.2 and 2.0 log MPN/g, respectively, after 48 h of Depuration at 22 degrees C. Decreasing water temperature to 15 degrees C increased the efficacy of Depuration in reducing V. parahaemolyticus and V. vulnificus in oysters. Reductions of V. parahaemolyticus and V. vulnificus in oysters increased to 2.1 and 2.9 log MPN/g, respectively, after 48 h of Depuration at 15 degrees C. However, Depurations at 10 and 5 degrees C were less effective than at 15 degrees C in reducing the Vibrio spp. in oysters. Extended Depuration at 15 degrees C for 96 h increased reductions of V. parahaemolyticus and V. vulnificus in oysters to 2.6 and 3.3 log MPN/g, respectively.