Rapid method for controlling the correct labeling of products containing common octopus (Octopus vulgaris) and main substitute species (Eledone cirrhosa and Dosidicus gigas) by fast real-time PCR

An Authentication Survey on Retail Seafood Products Sold on the Bulgarian Market Underlines the Need for Upgrading the Traceability System

Economically motivated or accidental species substitutions lead to economic and potential health damage to consumers with a loss of confidence in the fishery supply chain. In the present study, a three-year survey on 199 retail seafood products sold on the Bulgarian market was addressed to assess: (1) product authenticity by molecular identification; (2) trade name compliance to the list of official trade names accepted in the territory; (3) adherence of the list in force to the market supply. DNA barcoding on mitochondrial and nuclear genes was applied for the identification of whitefish (WF), crustaceans (C) and mollusks (cephalopods-MC; gastropods-MG; bivalves-MB) except for Mytilus sp. products for which the analysis was conducted with a previously validated RFLP PCR protocol. Identification at the species level was obtained for 94.5% of the products. Failures in species allocation were reconducted due to low resolution and reliability or the absence of reference sequences. The study highlighted an overall mislabeling rate of 11%. WF showed the highest mislabeling rate (14%), followed by MB (12.5%), MC (10%) and C (7.9%). This evidence emphasized the use of DNA-based methods as tools for seafood authentication. The presence of non-compliant trade names and the ineffectiveness of the list to describe the market species varieties attested to the need to improve seafood labeling and traceability at the national level.

Simultaneous Detection of Five Foodborne Pathogens Using a Mini Automatic Nucleic Acid Extractor Combined with Recombinase Polymerase Amplification and Lateral Flow Immunoassay

In recent years, foodborne disease outbreaks have caused huge losses to the economy and have had severe impacts on public health. The accuracy and variety of detection techniques is crucial to controlling the outbreak and spread of foodborne diseases. The need for instruments increases the difficulty of field detection, while manually-handled samples are subject to user error and subjective interpretation. Here, we use a mini automatic nucleic acid extractor combined with recombinant polymerase amplification (RPA) and lateral flow immunoassay (LFIA) for simultaneous quantitative detection of five major foodborne pathogens. The pre-treatment device using the magnetic bead method allows for nucleic acid extraction of the reagent tank without manual operation, which is highly efficient and stable for preventing aerosol contamination. The nuc gene of Staphylococcus aureus, the toxR gene of Vibrio parahaemolyticus, the rfbE gene of Escherichia coli O157:H7, the hlyA gene of Listeria monocytogenes, and the fimY gene of Salmonella enterica were used as target fragments. The labeled antibody concentration is optimized on the LFIA to find the equilibrium point for the binding capacity of the five chemical markers and to efficiently and accurately visualize the bands. The RPA assay shows an optimal performance at 37 °C for 15 min. The optimized RPA-LFIA detection limit can reach 10¹ CFU/mL. There was no cross-reactivity among forty-eight strains. Furthermore, the average recoveries in spiked food samples were 90.5–104.5%. In summary, the RPA-LFIA established in this study can detect five pathogenic bacteria simultaneously with little dependence on laboratory equipment, and it has promising prospects for screening in low-resource areas.

Development of a multiplex PCR assay for the simultaneous detection of big blue octopus (Octopus cyanea), giant Pacific octopus (Enteroctopus dofleini), and common octopus (Octopus vulgaris)

Since octopuses are similar in appearance and can be processed into various forms, seafood fraud has been reported. In this study, we developed the PCR assay to simultaneously detect three octopuses (big blue octopus, giant Pacific octopus, and common octopus). Specific primer sets were designed based on COI gene. We observed that the specific PCR amplicon sizes were 84 bp for big blue octopus, 117 bp for giant Pacific octopus, and 166 bp for common octopus, respectively. This assay was then used to test for specificity and did not show cross-reactivity with 15 cephalopods families. The limit of detection of the multiplex PCR assay was 0.1 pg. Subsequently, 30 commercial food products were then monitored to evaluate the applicability of this assay. All products were specifically amplified, and three octopus species of interest were distinguished. Therefore, this assay can be used as an octopus authentication tool in the seafood industry.

Tracking the provenance of octopus using isotopic and multi-elemental analysis

Octopus play an increasingly important role in ocean ecosystems and global fisheries, yet techniques for authenticating provenance are sorely lacking. For the first time, we investigate whether chemical profiling can distinguish geographical origins of octopus on international and domestic scales. Our samples consisted of wild-caught octopus from south-east Asia and southern Australia, regions with high seafood trade. We used a novel combination of stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotope analyses (Isotope-Ratio Mass Spectrometry) of internal calcified structures called statoliths, with elemental analyses (X-Ray Fluorescence using Itrax) of soft-tissue. We found that multivariate profiles exhibited distinctive regional signatures, even across species, with high classification success (∼95%) back to region of origin. This study validates isotopic and multi-elemental profiling as an effective provenance tool for octopus, which could be used to support transparency and accountability of seafood supply chains and thus encourage sustainable use of ocean resources.

A New Rapid Method for the Authentication of Common Octopus (Octopus vulgaris) in Seafood Products Using Recombinase Polymerase Amplification (RPA) and Lateral Flow Assay (LFA)

The common octopus (Octopus vulgaris) is a highly valued cephalopod species which is marketed with different grades of processing, such as frozen, cooked or even canned, and is likely to be mislabeled. Some molecular methods have been developed for the authentication of these products, but they are either labor-intensive and/or require specialized equipment and personnel. This work describes a newly designed rapid, sensitive and easy-to-use method for the detection of Octopus vulgaris in food products, based on Recombinase Polymerase Amplification (RPA) and a detection using a Lateral Flow assay (LFA). After studying several gene markers, a system of primers and nfo-probe was designed in the COI (Cytochrome Oxidase I) region and was successfully tested in 32 reference samples (covering 14 species) and 32 commercial products, after optimization. The method was also validated in a ring trial with eight European laboratories and represents a useful tool for food authenticity control at all levels of the value chain.

Lab experience with seafood control at the undergraduate level: Cephalopods as a case study

The correct labeling of seafood is important to protect nature and the rights of consumers. Given the certainty that the resources of the sea are not inexhaustible, only strict regulations and the implementation of sustainable fishing systems and reliable and traceable marketing systems can help ensure the long-term sustainability of fishery resources. Detecting mislabeling and seafood fraud is a useful resource for improving students' motivation and developing active learning methodologies in higher education. In the present study, we have proposed to the students a lab exercise consisting of exploring 25 different commercial cephalopod products from three major European supermarkets by using DNA barcoding and analyzing the results under the framework of EU and Spanish regulations. The problem is connected with the last theme (traceability) of the Conservation Genetics and Breeding course with the aim of providing students with a practical research lab experience about a real problem before going deeper into more theoretical contents. In this way, they can use the knowledge and the skills they acquired previously to better comprehend and think critically about the problem. Findings from students' answers to a survey revealed that the use of this approach generates useful information for communities, increases curiosity and feelings of benefit, and leads to high levels of satisfaction with lab practices compared with those in other courses. In conclusion, lab exercises focused on seafood control, in addition to being viable, can be used as a tool in classes to improve students' commitment to higher education.

A Real-Time PCR Method for the Authentication of Common Cuttlefish (Sepia officinalis) in Food Products

Cephalopods are very relevant food resources. The common cuttlefish (Sepia officinalis) is highly appreciated by consumers and there is a lack of rapid methods for its authentication in food products. We introduce a new minor groove binding (MGB) TaqMan real-time PCR (Polymerase Chain Reaction) method for the authentication of S. officinalis in food products to amplify a 122 base pairs (bp) fragment of the mitochondrial COI (Cytochrome Oxidase I) region. Reference and commercial samples of S. officinalis showed a threshold cycle (Ct) mean of 14.40, while the rest of the species examined did not amplify, or showed a significantly different Ct (p < 0.001). The calculated efficiency of the system was 101%, and the minimum DNA quantity detected was 10⁻⁴ ng. No cross-reactivity was detected with any other species, thus, the designed method differentiates S. officinalis from other species of the genus Sepia and other cephalopod species and works for fresh, frozen, grilled, cooked and canned samples of Sepia spp. The method has proved to be reliable and rapid, and it may prove to be a useful tool for the control of fraud in cuttlefish products.

Application of loop-mediated isothermal amplification (LAMP) for rapid detection of Atlantic cod (Gadus morhua), Pacific cod (Gadus macrocephalus) and haddock (Melanogrammus aeglefinus)

Codfish is a commercially important species of sea fish and plays an important role in the world fishery. In our study, two loop-mediated isothermal amplification (LAMP) assays (real-time fluorescence LAMP and visual LAMP) were established for the identification of three cod species in Gadidae (Gadus morhua, Gadus macrocephalus and Melanogrammus aeglefinus). 12S rDNA gene was used to design primers to distinguish the Gadidae and non-Gadidae species, and the mitochondrial Cytb gene was selected for discrimination of three cod species. After optimization, the 12S rDNA system and species-specific systems performed well, and target cod DNA could be detected in single or mixed samples. In the species-specific systems, the absolute limit of detection (LODa) of three cod species were 285, 37 and 197 pg/μL, and the relative limit of detection (LODr) reached to 1%, 0.1% and 1%, respectively. In the 12S rDNA system, the LODa of three cod species were 28.5, 37 and 19.7 pg/μL, respectively, and the LODr reached to 0.1%. Through the detection of 13 commercial cod products, the LAMP systems can detect cod contents in raw materials and deep-processed products as well. It indicated that the methods developed in this study have strong practicability and can meet the needs of routine testing.

The Expanding Role of Traceability in Seafood: Tools and Key Initiatives

In the last decade, a range of drivers within the seafood sector have incentivized the application of traceability to issues beyond food safety and inventory management. Some of the issues motivating the expanded use of traceability within the global seafood sector include: increased media attention on the legal and social risks within some seafood supply chains, governmental traceability requirements, private-sector sustainability commitments, and others. This article begins with an overview of these topics in the seafood industry, and why many nongovernment organizations (NGOs), companies, and government actors have turned to traceability as a tool to address them. We discuss how traceability connects to key requirements of environmental sustainability and social responsibility. Later, we review the range of traceability services, tools, software solutions, and the due diligence measures that are currently being leveraged within the seafood sector. The paper concludes with a discussion of several NGO- and industry-led traceability initiatives that are examples of seafood traceability improvements.

The development of a hexaplex-conventional PCR for identification of six animal and plant species in foodstuffs

A hexaplex-conventional PCR assay was developed for identification of five meat and one plant species origins in foodstuffs simultaneously. The method merges the use of horse (Equus caballus), soybean (Glycine max), sheep (Ovis aries), poultry (Meleagris meleagris), pork (Sus scrofa), and cow (Bos taurus) specific primers that amplify fragments (horse; 85 bp, soybean; 100 bp, sheep; 119 bp, poultry; 183 bp, pork; 212 bp and cow; 271 bp) of the mitochondrial cyt b, lectin, 12S rRNA, 12S rRNA, ATPase subunit 6 genes and ATPase subunit 8 genes respectively, and a universal 18S rRNA primers that amplifies a 141 bp. Multiplex analysis of the reference food samples showed that detection limit of the hexaplex assay was 0.01% for each species. Taken together, all data indicated that this hexaplex PCR assay was a simple, fast, sensitive, specific, and cost-effective detection method for horse, soybean, sheep, poultry, pork and cow species in foodstuffs.

Identification of four squid species by quantitative real-time polymerase chain reaction

Squids are distributed worldwide, including many species of commercial importance, and they are often made into varieties of flavor foods. The rapid identification methods for squid species especially their processed products, however, have not been well developed. In this study, quantitative real-time PCR (qPCR) systems based on specific primers and TaqMan probes have been established for rapid and accurate identification of four common squid species (Ommastrephes bartramii, Dosidicus gigas, Illex argentinus, Todarodes pacificus) in Chinese domestic market. After analyzing mitochondrial genes reported in GenBank, the mitochondrial cytochrome b (Cytb) gene was selected for O. bartramii detection, cytochrome c oxidase subunit I (COI) gene for D. gigas and T. Pacificus detection, ATPase subunit 6 (ATPase 6) gene for I. Argentinus detection, and 12S ribosomal RNA (12S rDNA) gene for designing Ommastrephidae-specific primers and probe. As a result, all the TaqMan systems are of good performance, and efficiency of each reaction was calculated by making standard curves. This method could detect target species either in single or mixed squid specimen, and it was applied to identify 12 squid processed products successfully. Thus, it would play an important role in fulfilling labeling regulations and squid fishery control.

Mislabelling and Species Substitution in Fishery Products Retailed in Sardinia (Italy), 2009-2014

Mislabelling and species substitution are major concerns for fishery products marketed in the EU. The present survey aimed to investigate the correct enforcement of the Community and National rules on the labelling and marketing of fishery products retailed in Sardinia (Italy) between 2009 and 2014. A total of 3000 labels for fresh unpacked fishery products have been considered. A total of 900 labels (30%) presented non-compliance concerning the wrong trade name, the wrong or missing information about the catch area and the production method. The highest percentage of mislabelling and species substitution has been detected in open-air markets (65%) and small-scale retail shops (40%) compared with the big supermarket chains (10%). The high percentage of non-compliances with the European and Italian legislation highlights the need to improve the essential information demanded by consumers on fishery products marketed in open-air markets and small-scale retail shops. While there are laws in place, it is unclear how effective they are and what type of penalties food business operators of open-air markets and small-scale retail shops may incur.