Juan M Vieites

ANFACO-CECOPESCA, Vigo, Galicia, Spain

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Publications (112)230.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In recent years a new genetic target for Vibrio cholerae detection has been reported, but its application was limited to clinical samples. This target, lolB, has never been applied to either food or environmental samples. In the present study the development, as well as the evaluation and pre-validation, of a real-time PCR method based on lolB, is described. The method included a newly designed hydrolysis probe to enhance its specificity. After comparison against other molecular and traditional methods, similar results were obtained regarding relative sensitivity, relative specificity, relative accuracy, positive and negative predictive values and index kappa of concordance (all higher than 91%), as well as a very low limit of detection (2 cfu/25 g). Additionally, after the analysis of more than 160 different food and environmental samples, its applicability in the food industry was completely demonstrated. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Food microbiology. 04/2015; 46:535-40.
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    ABSTRACT: Real-Time PCR is a very powerful tool with multiple applications in food microbiology, being pathogen detection the most important for food safety. In early January 2013 an increase in the incidence of Listeria monocytogenes was observed in a mussel-processing facility in the north-west of Spain. Then, a previously in-house validated qPCR method was applied to detect the contamination origin in the processing line. By the end of the same month a total of 62 samples from different spots in the processing plant were analyzed, obtaining 25 positive results by qPCR. All the isolates, identified as L. monocytogenes, presented the same biochemical profile and belonged to the same molecular typing group (Group 3). After the identification and elimination of the contamination source, 25 additional samples were analyzed over the following nine months, without any positive sample. Results obtained showed that the qPCR method is a suitable technique to identify the exact source of contamination that could appear in food processing plants, saving time respect to traditional culture methods.
    Food Control 12/2014; 46:319–323. · 2.74 Impact Factor
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    ABSTRACT: Consumption of Lepidocybium flavobrunneum and Ruvettus pretiosus is related with the gastrointestinal disease called Keriorrhea. Sometimes, intentionally or not, these species are mislabelled as other harmless species, causing severe disruptions to consumers. The correct identification of these species helps to avoid food fraud and health problems. For this reason, a multiplex Real Time-PCR method based on TaqMan technology for the correct authentication of L. flavobrunneum and R. pretiosus has been developed. The method is based on a species-specific set of primers and TaqMan probe which amplifies a 276 bp fragment of the cytochrome oxidase I (COI) mitochondrial DNA region. This methodology allows your application to any type of product, regardless of the degree of processing it has undergone with high specificity, sensitivity and rapidity. Also, it might be a useful tool in monitoring and verifying labelling regulation and protect consumer rights.
    Food Chemistry. 11/2014;
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    ABSTRACT: Harmful algal blooms (HABs) are excessive accumulation of phytoplankton that produce biotoxins oradversely affect humans and animals. Among all microalgae, the genus Prorocentrum biosynthesizes toxins responsible for the human syndrome known as diarrhetic shellfish poisoning (DSP), one of the most frequent in Spanish coasts. HABs impact on the public health, fisheries, ecosystem and tourism have increased over the past few decades being an important and widespread problem. Therefore, the development of control methods to minimize the risks derived from these events is a matter of vital importance. The use of clay for removing microalgae has been previously explored. Clay flocculation is based on the physical and chemical properties of the mineral particles in aqueous suspensions. In this preliminary work various types of clay were investigated to evaluate the adsorption and flocculation properties in seawater containing Prorocentrum lima dinoflagellates. We set up water columns with cells of Prorocentrum lima from an established in vitro culture. Then we added different types of clays to a final concentration of 0.2%. The experimental results confirmed the cell removal through the flocculation of algal and mineral particles leading to the formation of aggregates, which rapidly settle and further entrain cells during their descent. The reduction in the number of cells was time dependent and noticeable within several minutes exposure to clays.Moreover, the microscopy images of the samples enable to observe the clays in aggregates of two or more cells where the mineral particles were bound to the outer membranes of the dinoflagellates. Therefore, this preliminary data offers promising results to use these clays for the mitigation of HABs.
    II International Scientific Symposium On Innovation In Marine Products And Food Industry, Vigo, Spain.; 09/2014
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    ABSTRACT: Food allergy is recognised as an important human health problem. Fish represent one of the most important causes of food hypersensitivity reaction. Small amounts of the allergen can cause severe reactions in sensitive individuals, so correct labelling is essential to ensure the protection of consumers. The objective of the present work was to develop a reliable, sensitive and specific real-time PCR method for the detection of fish and traces of fish in all kind of products included those that have undergone aggressive treatments such as high temperature or pressure. This methodology was validated simulating products likely to contain this allergen and spiking them with fish cooking water. In addition, a comparison between the performance of in-house methodology and a commercial kit, both of them based on real-time PCR, was carried out. This work is relevant because it is the first, rapid real-time PCR method developed to date for the detection of fish in processed food products. The results obtained confirm the present assay is a useful tool in detecting fish and, therefore, minimising exposure and reducing incidences of allergic reaction to fish in contaminated products.
    Food Chemistry 05/2014; 151:415-20. · 3.33 Impact Factor
  • Martiña Ferreira, Jorge Lago, Juan Manuel Vieites, Ana G Cabado
    Seafood and Freshwater Toxins: Pharmacology, Physiology, and Detection. 01/2014; 14:291.
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    ABSTRACT: Part of the new IFST Advances in Food Science Series, Seafood Processing: Technology, Quality and Safety covers the whole range of current processes which are applied to seafood, as well as quality and safety aspects. The first part of the book (‘Processing Technologies’) covers primary processing, heating, chilling, freezing, irradiation, traditional preservation methods (salting, drying, smoking, fermentation, etc), frozen surimi and packaging. The subjects of waste management and sustainability issues of fish processing are also covered. In the second part (‘Quality and Safety Issues’), quality and safety analysis, fish and seafood authenticity and risk assessment are included.
    Seafood Processing: Technology, Quality and Safety, Edited by Ioannis S. Boziaris, 01/2014: chapter Fish and Seafood: pages 421-454; JOHN WILEY & SONS, LTD., ISBN: 978-1-118-34621-1
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    ABSTRACT: Enteromyxum scophthalmi is a myxozoan parasite that causes severe parasitic diseases in cultured turbot affecting mainly the intestine of the host. It is characterized by producing acute enteritis, starvation and eventually death. Current diagnosis of E. scopthalmi use traditional techniques, based on the identification of the morphology of the parasite. These techniques take extended time to be carried out and do not favour the adoption of control measure at turbot farms and require the sacrifice of fish. This study develops a fast real-time PCR molecular tool for the detection of E. scophthalmi in infected farmed turbot. This methodology is applicable for routine controls on the farm at every stage of the parasite infection. Results of the study demonstrate the robustness, specificity, efficiency and reliability of the technique. In addition, this study also provides a non-invasive procedure of sampling through swaps. This allows control, prevention and diagnosis of the parasite infection at turbot farms while maintaining the welfare of the cultivated fish and avoiding sacrifice of the fish sampled.
    Aquaculture Research 01/2014; · 1.42 Impact Factor
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    ABSTRACT: The EU FP7 funded project \“Bio-engineered micro Encapsulation of Active agents Delivered to Shellfish (BEADS)” is focused on mitigating the impact of marine biotoxins (ASP/DSP), microbial contamination (bacteria/norovirus) and the parasitic protozoan Bonamia ostreae on shellfish aquaculture. Purpose: to develop probiotic diets and a microencapsulated delivery system in the digestive tract of shellfish to improve depuration. Feeding experiments were performed to identify the optimum size of alginate microcapsules, testing three different sizes and colours containing nondegradable fluorescent dye microbeads. Oysters and mussels were placed in tanks containing filtered seawater. Three sizes of microcapsules were mixed and shellfish were fed for 3 hours. Shellfish were removed during the feeding period at 0.5, 1, 2 and 3 hours and dissected. Any capsules remaining in the water and in the digestive organs of shellfish were extracted and measured using a fluoroskan analyzer. A higher concentration of the smaller capsules was found in the digestive gland, indicating that the smaller capsules were preferentially ingested. The ingestion increased during the three-hour period. Fluorescent beads of different colours embedded in alginate capsules were observed bound to the mucus string. Mussels were more efficient than oysters in incorporating alginate beads that were observed by light microscopy as intact in the digestive gland of mussels and oysters during feeding period. Broken alginate beads were found in faeces. During passage through the intestine, active agents embedded by alginate capsules are released into the digestive gland providing a useful tool to transport active agents.
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    ABSTRACT: A total of 84 samples of wild and farmed fish, cephalopods and fish oils for animal feeding, traded in Spain, were analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in 2009-2012, by gas chromatography-ion trap tandem mass spectrometry (GC-MS-MS). The method was optimised for screening at moderate costs, allowing PCDD/Fs determination at 1 pg World Health Organization-toxic equivalent quantities (WHO-TEQ) g(-1) wet weight (w w) and dl-PCBs at 0.02 pg WHO-TEQ g(-1) w w. Concentrations in fish and cephalopods ranged from values below the limit of detection to 1.7 pg g(-1) WHO-TEQ sum PCDD/Fs and dl-PCBs, considered as safe with regard to EU legislation. Higher levels were found in cod livers (5.4-54.2) and fish oils (3.3-30.7), with one noncompliant sample in each group.
    Food Additives and Contaminants: Part B Surveillance 09/2013; 6(3):218-230.
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    ABSTRACT: A wide variety of qPCR methods currently exist for Salmonella spp., Escherichia coli O157 and Listeria monocytogenes detection. These methods target several genes and use different detection chemistries, either in simplex or in multiplex formats. However, the majority of these methods have not been carefully validated, and the number of validated methods that use multiplex qPCR is even lower. The aim of the present study was to develop and validate a multiplex qPCR method from previously validated simplex qPCR primers and probes. A modified broth medium was selected and primary and secondary enrichment times were further optimized. Efficiency of the newly combined qPCR system was comprised between 91% and 108%, for simplex and multiplex analyses. A total of 152 food and environmental, natural and spiked samples, were analyzed for the evaluation of the method obtaining values above 91% that were reached for all the quality parameters analyzed. A very low limit of detection (5cfu/25g after enrichment) for simultaneous identification of these 3 pathogens was obtained.
    International journal of food microbiology 04/2013; 164(1):92-98. · 3.01 Impact Factor
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    ABSTRACT: The toxic effects of the organotin compounds MBT, DBT and TBT were evaluated in vitro in a Neuroblastoma human cell line. Mechanisms of cell death, apoptosis vs. necrosis, were studied by using several markers: inhibition of cell viability and proliferation, F-actin and mitochondrial membrane potential changes as well as ROS production and DNA fragmentation. The most toxic effects were detected with DBT and TBT even at very low concentrations (0.1 - 1 µM). In contrast MBT induced lighter cytotoxic changes at the higher doses tested. None of the studied compounds stimulated PI uptake, although the most toxic chemical, TBT, caused LDH release at the higher concentrations tested. These findings suggest that in Neuroblastoma, OTC-induced cytotoxicity involves different pathways depending on the compound, concentration and incubation time. A screening method, for DBT and TBT quantification was developed based on cell viability loss, allowing a fast detection alternative to complex methodology.
    Journal of Agricultural and Food Chemistry 03/2013; · 3.11 Impact Factor
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    ABSTRACT: Despite efforts done by industries some well known foodborne pathogens, like Salmonella spp. and Listeria monocytogenes, continue to be a challenge to public health institutions and a threat for consumers. The aim of this study was to develop a complete, rapid and reliable multiplex real-time PCR (qPCR) method for the simultaneous detection of these two bacteria in food and environmental samples, including a novel single enrichment broth (TA10) for both bacteria. TA10 broth was modified (pH and buffer concentration) to enhance simultaneous growth of both pathogens in the presence of high numbers of competitors bacteria. Also two different DNA-extraction protocols were compared. qPCR efficiency above 90% was obtained, covering 5 orders of magnitude. Complete method achieved low limit of detection (5 cfu/25 g), and all quality parameters of the method returned values over 90%. Complete qPCR method was applied to 95 natural samples covering a wide variety of food types proving that the qPCR method described, including the use of one single enrichment broth, modified TA10, was suitable for the simultaneous and reliable screening of Salmonella spp. and L. monocytogenes in food and environmental samples.
    Food Control. 03/2013; 30(1):76–85.
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    ABSTRACT: An interlaboratory collaborative study to validate a colorimetric phosphatase inhibition assay for quantitative determination of the okadaic acid (OA) toxins group in molluscs, OkaTest, was conducted. Eight test materials, including mussels, scallops, clams, and cockles, were analyzed as blind duplicates. Blank samples and materials containing different OA toxin levels ranging from 98 to 275 microg/kg OA equivalents were included. The study was carried out by a total of 16 laboratories from 11 different countries. Values obtained for repeatability relative standard deviations (RSDr) ranged from 5.4 to 11.2% (mean 7.5%). Reproducibility RSD (RSD(R)) values were between 7.6 and 13.2% (mean 9.9%). The Horwitz ratio (HorRat) values ranged between 0.4 and 0.6. A recovery assay was also carried out using a sample spiked with OA. A mean recovery of 98.0% and an RSD of 14.5% were obtained. The results obtained in this validation study indicate that the colorimetric phosphatase inhibition assay, OkaTest, is suitable for quantitative determination of the OA toxins group. OkaTest could be used as a test that is complementary to the reference method for monitoring the OA toxins group.
    Journal of AOAC International 01/2013; 96(1):77-85. · 1.23 Impact Factor
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    ABSTRACT: Economic importance of gadoids such as fishing resource, and their conservation status, necessitates the development of techniques that allow unequivocal authentication of products made from them. Amplification of a fragment of mitochondrial cytochrome b (cyt b) marker and subsequent phylogenetic analysis were carried out to authenticate these products and assure their correct labeling. Also, SNP analysis that allows detection of species mixtures of Gadus genus was developed. For this, two fragments of the cyt b gene were amplified and sequenced, one of 464 bp and another internal fragment to this of 263 bp to allow the authentication of gadoid species in highly processed products. Obtained sequences were aligned and analyzed in order to assess the presence of informative variable positions and a maximum of 14 SNP were identified and selected. These allow detection and identification of species mixtures belonging to this genus. The developed methodologies were validated and applied to 25 commercial samples. The main novelty of this work lies in the fact that is the only work that allows the detection of species mixtures of the Gadus genus and is the only one that allows the authentication of highly processed products up to date. Furthermore, this methodology allows identifying more of 15 species of gadoids and can be applied to all kinds of seafood products. Therefore, this molecular tool can be applied in questions related to check the fulfillment of labeling regulations for seafood products, verify the correct traceability in commercial trade and for fisheries control.
    European Food Research and Technology 01/2013; 236(1). · 1.39 Impact Factor
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    ABSTRACT: Prepared by a team of specialists, this volume presents the latest molecular methods for determining the presence of constituents that make a food what it is claimed to be. By clarifying the theory and applications of DNA, peptide, and lipid technologies, the book presents information required to identify molecular markers whose presence defines the quality and provenance of meats, seafood, cheeses, oils, wines, cereal products and other foods. The text provides critical tools and data needed to augment routine food analysis and enhance food safety by aiding in the detection of counterfeit, and potentially deleterious, foods. From the Preface Modern analytical techniques have made it possible in many cases (at least theoretically) to detect and objectively measure an "authentic" characteristic claimed to be a "quality" attribute. Most of the time, such measurement can be achieved by identifying and measuring organic molecules in the food or food product. In a word, we can use one or more molecules as markers for the alleged authenticity. The aim of this book is to present the most important cases, including major food commodities and major organic compounds in them, where organic molecules can be used as molecular markers for food authenticity. The book offers practical and background information on applying biomolecular and chemical techniques to determine the source and ingredients of food products, to help prevent fraud and thereby improve food safety by not exposing consumers to counterfeit products.
    Food Authentication Using Bioorganic Molecules, Edited by Stefano Sforza, 01/2013: chapter Authentication and Traceability of Fish and Seafood Species by Means of Molecular Tools: pages 259-294; Destech Publications SL., ISBN: 978-1-60595-045-7
  • Montserrat Espiñeira, Juan M Vieites
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    ABSTRACT: The TaqMan real-time PCR has the highest potential for automation, therefore representing the currently most suitable method for screening, allowing the detection of fraudulent or unintentional mislabeling of species. This work describes the development of a real-time polymerase chain reaction (RT-PCR) system for the detection and identification of common octopus (Octopus vulgaris) and main substitute species (Eledone cirrhosa and Dosidicus gigas). This technique is notable for the combination of simplicity, speed, sensitivity and specificity in an homogeneous assay. The method can be applied to all kinds of products; fresh, frozen and processed, including those undergoing intensive processes of transformation. This methodology was validated to check how the degree of food processing affects the method and the detection of each species. Moreover, it was applied to 34 commercial samples to evaluate the labeling of products made from them. The methodology herein developed is useful to check the fulfillment of labeling regulations for seafood products and to verify traceability in commercial trade and for fisheries control.
    Food Chemistry 12/2012; 135(4):2439-44. · 3.33 Impact Factor
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    ABSTRACT: Meat is a significant source of high-quality nutrients, which are very important in the diet. Among meat products, one of the most prized is bovine meat, of which male beef has been designated to be of a higher quality. However, because of its similarity with female beef, deliberate or unintentional substitutions can occur. To avoid this, methodology based on the fast real-time polymerase chain reaction has been developed to authenticate the species and gender origin of beef. This technique consists of two polymerase chain reactions: one bovine-specific reaction and another Y-chromosome-specific multiplex reaction. This methodology has been validated for all kinds of beef products, including those subjected to intensive processing treatments, and it has subsequently been applied to 10 commercial samples labelled as ox to determine whether they are properly labelled. This assay has been shown to have high specificity, sensitivity and rapidity, with the potential to be a powerful tool in enforcing food labelling regulations.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 11/2012;
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    ABSTRACT: SUMMARY Global aquaculture production of turbot has rapidly increased worldwide in the last decade and it is expected to have even bigger growth in the next years due to new farms operating. The losses caused by pathogen infections have grown at the same time as the production of this species. Parasitological infections are among the main relevant pathologies associated with its culture and produce serious losses in aquaculture, reduce the growth rate in fish and may lead to unmarketable fish due to skeletal muscle abnormalities in cases with high intensity of infection. The microsporidian parasite Tetramicra brevifilum causes severe infections and generates major losses in farmed turbot. Infections are difficult to control due to spore longevity and its direct transmission. To facilitate the infection management, an effective tool for fast detection and identification of T. brevifilum is needed. This study provides a molecular methodology of fast Real-Time PCR for T. brevifilum detection to the aquaculture industry, useful for routine control of T. brevifilum at turbot farms. The method is characterized by its high specificity and sensitivity, and it can be applied to cultured turbot for parasite detection regardless of the life-cycle stage of the pathogen or the infection intensity.
    Parasitology 10/2012; · 2.36 Impact Factor
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    ABSTRACT: Microalgae are the main component of first tropic level in aquatic food chain; it is for this reason that they are used as food in aquaculture. Also due to its biotechnological potential properties, they are used in the production of diverse components, dyes, antioxidants, enzymes, emulsifiers, etc. The extended ways of microalgae applications require physiologically and genetically stable cultures as well as correctly identified organisms to guarantee reproducibility and reliability. But the variety of species and the morphological similarity between some of them make difficult the identification of some microalgae. The use of molecular markers has supplied a very useful tool for identification of microalgae in fast mode, such as in classification. The present study has worked on the molecular characterization of main species of microalgae used in aquaculture in base of the molecular markers 18S rRNA and 16S rRNA. Microalgae DNA has been amplified and sequenced, and the resultant sequences were analyzed and reflected in phylogenetic trees. The phylogenetic analyses obtained reflect as both molecular markers allow to differentiate the main genus used in aquaculture.
    Aquaculture International 10/2012; In Press. · 1.04 Impact Factor

Publication Stats

820 Citations
230.30 Total Impact Points


  • 1996–2013
      Vigo, Galicia, Spain
  • 1996–2012
    • University of Vigo
      • Faculty of Biology
      Vigo, Galicia, Spain
  • 1999–2010
    • University of Santiago de Compostela
      • Facultad de Veterinaria
      Santiago de Compostela, Galicia, Spain
  • 2001–2003
    • Centro de Supercomputación de Galicia
      Santiago, Galicia, Spain