DNA barcoding as a tool for detecting mislabeling of fishery products imported from third countries: An official survey conducted at the Border Inspection Post of Livorno-Pisa (Italy)

Can consumers avoid mislabelling? Genetic species identification provides recommendations for shrimp/prawn products

BACKGROUND

Crustaceans of the superfamily Penaeoidea (e.g., shrimps and prawns) are among the most commercially available aquatic products worldwide. However, there are few studies regarding not only the presence but also the characteristics of mislabelling in these food products. Such information would be helpful for consumers in order to avoid the typical problems associated with mislabelling (e.g., health and economic issues). For this reason, this work considers Penaeoidea mislabelling by comparing different products (frozen, fresh, boiled), and sources (hypermarkets, supermarkets and fishmongers) from Spain (Europe).

RESULTS

A total of 94 samples from 55 different products were collected, representing 19 different species from 13 genera. Mitochondrial DNA (COI gene) was amplified, revealing mislabelling in almost 30% of supermarket products and almost exclusively found in frozen samples (95% of the total) regardless of its price. In addition, products from the Pacific Ocean seem to be particularly susceptible to mislabelling.

CONCLUSIONS

All in all, recommendations for the consumer in order to avoid mislabelling of prawns include purchasing them fresh from fishmongers; aquaculture products must not be avoided. This study represents, to our knowledge, the first attempt to provide recommendations to consumers based on DNA analyses in order to avoid mislabelling in food products. Further research is therefore required to provide such recommendations in different food products, particularly those that are processed, packaged and/or frozen. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A synergistic solution for fighting fraudulent practices in squid using light stable isotope ratios and lanthanide tracers

To identify a novel optimized strategy for preventing fraudulent substitutions of squid species and origins, forty European squids (Loligo vulgaris) and forty flying squids (Todarodes sagittatus) from the Mediterranean Sea and Atlantic Ocean were analyzed for δ13C, δ15N, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu using isotope ratio mass spectrometry and inductively coupled plasma-mass spectrometry. While δ13C and δ15N variations were mainly species-related, they alone could not reliably distinguish samples. To address this issue, decision rules were developed using Classification and Regression Tree analysis. Threshold values for δ13C (-19.91‰), δ15N (14.87‰), and Pr (0.49 μg kg-1) enabled successful discrimination among Mediterranean European squids, Atlantic European squids, Mediterranean flying squids, and Atlantic flying squids, achieving over 90% accuracy, 81% precision, 80% sensitivity, and 93% specificity. This method holds promise for enhancing traceability and safety in the seafood industry, ensuring product integrity and consumer trust.

Use of Biomolecular Tools to Control the Labels of Ethnic Food Coming from Eastern Europe

In recent years, due to the large Romanian community present in Italy, the retail of foods coming from Eastern Europe has increased. The most common type of violation detected in these foods consists of incorrect labeling and species-replacement frauds. In this paper, the compliance of labels of 43 ethnic processed food coming from Eastern Europe and commercialized in Italy was evaluated by means of PCR and Sanger sequencing. Our data revealed 33% of non-compliant labels in samples containing swine, ruminants, and avian ingredients. These results demonstrate that PCR can be easily used for the identification of species in highly processed products, proving to be a rapid, effective, and economic method. On the other hand, samples reporting fish as ingredients highlighted the ineffectiveness of the applied sequencing protocol, due to the low informative property of targeted fragments or to the lack of consensus sequences in the case of uncommon species.

Authentication of the species identity of squid rings using UHPLC-Q-Orbitrap MS/MS-based lipidome fingerprinting and chemoinformatics

Species mislabeling of commercial loliginidae squid can undermine important conservation efforts and prevent consumers from making informed decisions. A comprehensive lipidomic fingerprint of Uroteuthis singhalensis, Uroteuthis edulis, and Uroteuthis duvauceli rings was established using high-resolution mass spectrometry-based lipidomics and chemoinformatics analysis. The principal component analysis showed a clear separation of sample groups, with R2X and Q2 values of 0.97 and 0.85 for ESI+ and 0.96 and 0.86 for ESI-, indicating a good model fit. The optimized OPLS-DA and PLS-DA models could discriminate the species identity of validation samples with 100 % accuracy. A total of 67 and 90 lipid molecules were putatively identified as biomarkers in ESI+ and ESI-, respectively. Identified lipids, including PC(40:6), C14 sphingomyelin, PS(O-36:0), and PE(41:4), played an important role in species discrimination. For the first time, this study provides a detailed lipidomics profile of commercially important loliginidae squid and establishes a faster workflow for species authentication.

Morphological, molecular identification and evaluation of antioxidant activity of seahorses from the Moroccan coasts

Seahorses, part of the small marine teleost fish family Syngnathidae, are increasingly under threat due to habitat degradation and overfishing. Notably used in traditional Chinese medicine, these fish have demonstrated significant pharmacological and cosmetic properties. In Morocco, however, seahorses are minimally exploited. This study aims to explore the biodiversity of Moroccan seahorses, focusing on identifying species from the Atlantic and Mediterranean coasts both morphologically and molecularly, and evaluating their antioxidant activity. The research involved collecting 62 dried seahorses from local fishermen. These specimens were subjected to detailed morphological and molecular identification through the DNA barcoding method, concentrating on the mitochondrial marker Cytochrome Oxidase I (COI) gene. Following DNA extraction and amplification, the sequences were analyzed for species identification and phylogenetic relationships. Additionally, the antioxidant activities of the seahorses were quantified using assays such as ABTS, reducing power, phosphomolybdenum, and β-carotene-linoleic acid. The combined morphological and molecular analyses consistently identified all specimens as Hippocampus hippocampus, and phylogenetic trees suggested a close relation with European and Turkish counterparts. Furthermore, the antioxidant assays revealed significant activity, with the ABTS assay showing an IC50 of 14.571 mg/mL ± 0.334, and the β-carotene-linoleic acid assay showing an IC50 of 1.273 mg/mL ± 0.166. The reducing power and phosphomolybdenum assays recorded EC50 values of 1.868 mg/mL ± 0.033 and 1.156 mg/mL ± 0.112, respectively. These results confirm the high antioxidant potential of Moroccan seahorses, suggesting their therapeutic value and necessitating measures for their biodiversity preservation at a national level.

Seafood label quality and mislabelling rates hamper consumer choices for sustainability in Australia

Seafood mislabelling and species substitution, compounded by a convoluted seafood supply chain with significant traceability challenges, hinder efforts towards more sustainable, responsible, and ethical fishing and business practices. We conducted the largest evaluation of the quality and accuracy of labels for 672 seafood products sold in Australia, assessing six seafood groups (i.e., hoki, prawns, sharks and rays, snapper, squid and cuttlefish, and tuna) from fishmongers, restaurants, and supermarkets, including domestically caught and imported products. DNA barcoding revealed 11.8% of seafood tested did not match their label with sharks and rays, and snappers, having the highest mislabelling rate. Moreover, only 25.5% of products were labelled at a species-level, while most labels used vague common names or umbrella terms such as 'flake' and 'snapper'. These poor-quality labels had higher rates of mislabelling than species-specific labels and concealed the sale of threatened or overfished taxa, as well as products with lower nutritional quality, reduced economic value, or potential health risks. Our results highlight Australia's weak seafood labelling regulations and ambiguous non-mandatory naming conventions, which impede consumer choice for accurately represented, sustainable, and responsibly sourced seafood. We recommend strengthening labelling regulations to mitigate seafood mislabelling and substitution, ultimately improving consumer confidence when purchasing seafood.

Quality analysis of genomic DNA and authentication of fisheries products based on distinct methods of DNA extraction

Molecular genetic techniques are an effective monitoring tool, but high-quality DNA samples are usually required. In this study, we compared three different protocols of DNA extraction: NaCl (saline); phenol-chloroform and commercial kit (Promega)-from three biological tissues of five individuals of Lutjanus purpureus under two methods of storage. The evaluated items included DNA concentration and purity, processing time and cost, as well as the obtaining of functional sequences. The highest average values of DNA concentration were obtained using the saline procedure and the commercial kit. Pure DNA was only obtained using the saline protocol, evaluated by the ratio of 260/280. The saline and phenol-chloroform protocols were the least expensive methods. The commercial kit costs are counterbalanced by the short time required. The procedure based on phenol-chloroform presented the worst results regarding DNA yield and the time required to perform all steps. The saline and commercial kit protocols showed similar results concerning the amount and quality of extracted DNA. Therefore, the final choice should be based on the available financial resources and the available time for carrying out each procedure of DNA extraction.

Elemental and spectral chemometric analyses of Octopus vulgaris beaks as reliable markers of capture location

The high demand and economic relevance of cephalopods make them prone to food fraud, including related to harvest location. Therefore, there is a growing need to develop tools to unequivocally confirm their capture location. Cephalopod beaks are nonedible, making this material ideal for traceability studies as it can also be removed without a loss of commodity economic value. Within this context, common octopus (Octopus vulgaris) specimens were captured in five fishing areas along the Portuguese coast. Untargeted multi-elemental total X-ray fluorescence analysis of the octopus beaks revealed a high abundance of Ca, Cl, K, Na, S, and P, concomitant with the keratin and calcium phosphate nature of the material. We tested a suite of discrimination models on both elemental and spectral data, where the elements contributing most to discriminate capture location were typically associated with diet (As), human-related pressures (Zn, Se, and Mn), or geological features (P, S, Mn, and Zn). Among the six different chemometrics approaches used to classify individuals to their capture location according to their beaks' element concentration, classification trees attained a classification accuracy of 76.7%, whilst reducing the number of explanatory variables for sample classification and highlighting variable importance for group discrimination. However, using X-ray spectral features of the octopus beaks further improved classification accuracy, with the highest classification of 87.3% found with partial least-squares discriminant analysis. Ultimately, element and spectral analyses of nonedible structures such as octopus beaks can provide an important, complementary, and easily accessible means to support seafood provenance and traceability, whilst integrating anthropogenic and/or geological gradients.

The 11 sins of seafood: Assessing a decade of food fraud reports in the global supply chain

Due to complex, valuable, and often extremely opaque supply chains, seafood is a commodity that has experienced a high prevalence of food fraud throughout the entirety of its logistics network. Fraud detection and prevention require an in-depth understanding of food supply chains and their vulnerabilities and risks so that food business operators, regulators, and other stakeholders can implement practical countermeasures. An analysis of historical criminality within a sector, product, or country is an important component and has not yet been conducted for the seafood sector. This study examines reported seafood fraud incidents from the European Union's Rapid Alert System for Food and Feed, Decernis's Food Fraud Database, HorizonScan, and LexisNexis databases between January 01, 2010 and December 31, 2020. Illegal or unauthorized veterinary residues were found to be the most significant issue of concern, with most reports originating from farmed seafood in Vietnam, China, and India. For internationally traded goods, border inspections revealed a significant frequency of reports with fraudulent or insufficient documentation, indicating that deceptive practices are picked up at import or export but are occurring further down the supply chain. Practices such as species adulteration (excluding veterinary residues), species substitution, fishery substitution, catch method fraud, and illegal, unreported, and unregulated fishing were less prevalent in the databases than evidenced in the scientific literature. The analysis demonstrates significant differences in outcomes depending on source and underlines a requirement for a standardized and rigorous dataset through which food fraud can be scrutinized to ensure enforcement, as well as industry and research resources are directed accurately. Practical Application: Levels of historic food fraud in a product, sector, supply chain node or geographic location provide an indication of historic criminality, the methods used and the location of reported frauds. This study provides an overview of historic levels of seafood fraud that can be used to inform seafood fraud prevention and mitigation activities by the food industry, regulators and other stakeholders.

Development of a DNA Metabarcoding Method for the Identification of Bivalve Species in Seafood Products

The production of bivalve species has been increasing in the last decades. In spite of strict requirements for species declaration, incorrect labelling of bivalve products has repeatedly been detected. We present a DNA metabarcoding method allowing the identification of bivalve species belonging to the bivalve families Mytilidae (mussels), Pectinidae (scallops), and Ostreidae (oysters) in foodstuffs. The method, developed on Illumina instruments, targets a 150 bp fragment of mitochondrial 16S rDNA. We designed seven primers (three primers for mussel species, two primers for scallop species and a primer pair for oyster species) and combined them in a triplex PCR assay. In each of eleven reference samples, the bivalve species was identified correctly. In ten DNA extract mixtures, not only the main component (97.0-98.0%) but also the minor components (0.5-1.5%) were detected correctly, with only a few exceptions. The DNA metabarcoding method was found to be applicable to complex and processed foodstuffs, allowing the identification of bivalves in, e.g., marinated form, in sauces, in seafood mixes and even in instant noodle seafood. The method is highly suitable for food authentication in routine analysis, in particular in combination with a DNA metabarcoding method for mammalian and poultry species published recently.

Investigating seafood substitution problems and consequences in Taiwan using molecular barcoding and deep microbiome profiling

Seafood is commonly seen in cuisines of the Asia–Pacific regions. The rates and consequences of seafood substitution frauds in Taiwan were elusive. To address this, we conducted a consumer-centered study, collecting seafood dishes and cooking materials from restaurants and markets easily accessible to the residents in Taiwan. Seafood substitutions were evaluated using DNA barcodes in the mitochondrial MT-CO1 gene. Among the 127 samples collected, 24 samples were mislabeled (18.9%, 95% Confidence interval [CI] = [12.5–26.8%]). The mislabel rates vary in different fish and product types (snapper [84.6%, 54.6–98.1%], cod [25%, 5.5–57.2%], swordfish [16.7%, 2.1–48.4%], cobia [16.7%, 0.4–64.1%], surimi products [100.0%]). A deep microbiome profiling was performed in 8 correctly-labeled conventional sushi and 2 tilapia sashimi mislabeled as snapper, with sequencing depths greater than 100,000 reads for every sample. The relative abundance of Pseudomonas genus is significantly higher in tilapia sashimi than in conventional sushi (P = 0.044). In conclusion, the gross seafood mislabel rate in Taiwan is 18.9% (12.5–26.8%). Snapper, cod and surimi products are particularly vulnerable to fraudulent substitutions. The high abundance of Pseudomonas in tilapia sashimi mislabeled as snapper unveils a potential health issue pertaining to the consumption of raw mislabeled seafood.

DNA barcoding reveals mislabeling and commercial fraud in the marketing of fillets of the genus Brachyplatystoma Bleeker, 1862, the Amazonian freshwater catfishes economically important in Brazil

The substitution and mislabeling is facilitated by the processing of fish products. We employed a DNA barcoding to authenticate fillets labeled as "dourada" (Brachyplatystoma rousseauxii), and "piramutaba" (Brachyplatystoma vaillantii) marketed in the Brazil. A 615 bp of the Cytochrome oxidase subunit I (COI) was sequenced from 305 fillets and subsequently identified to species level by querying public databases and sequences of reference species. The results revealed a global mean substitution rate of 17%. The highest substitution rate was detected in "dourada" (26%), the most valuable species, followed by "piramutaba" (9%). The most cases of substitutions were by species of lower commercial value, suggesting fraud aimed at increased profits. Therefore, we suggest the improvement of food-labeling regulation, continued inspection, as well as the adoption of the DNA barcode for the molecular authentication of processed fish to prevent substitution of these products in Brazil.

Determining the Authenticity of Shark Meat Products by DNA Sequencing

Given that the global shark meat market is poised to grow in future years, the aim of this study was to use DNA sequencing of the cytochrome c oxidase I (COI) and NADH dehydrogenase subunit 2 (NADH2) mitochondrial genes to examine the market of shark meat products in Italy. This made it possible to analyze patterns of species utilization and commercialization of threatened, endangered and/or prohibited species, focusing on fraudulent activities in the shark food chain in order to propose seafood safety and environmental sustainability solutions. The study shows that the labeling of shark meat products generally lacks comprehensive information, thus making it difficult for consumers to make informed purchasing decisions and fails to comply with European Union (EU) legislation regarding seafood labelling. Molecular investigation reveals a high mislabeling rate (45.4%), highlighting widespread use of cheaper species either in order to replace species that are better known and more popular, or else in order to sell various threatened species. Considering that seafood mislabeling can circumvent the management of sustainable fisheries and facilitate Illegal, Unreported and Unregulated (IUU) fishing, the routine use of genetic analysis should be encouraged among control and enforcement agencies in order to implement effective management measures. This would help to build a species-specific reporting system for all catches, and enhance control measures, in order to prevent illegal activities connected with shark catches and trade around the world.

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.

DNA Barcoding Revealed Mislabeling and Potential Health Concerns with Roasted Fish Products Sold across China

HIGHLIGHTS

75.5% of products were identified as species outside the expected family. Six products were identified as containing multiple species from distinct families. Species from distinct families were verified in products of same brand for six groups. Identification of potentially toxic pufferfish species highlighted health concerns.

Building a DNA barcode library for the freshwater fishes of Bangladesh

We sequenced the standard DNA barcode gene fragment in 694 newly collected specimens, representing 243 species level Operational Barcode Units (OBUs) of freshwater fishes from Bangladesh. We produced coi sequences for 149 out of the 237 species already recorded from Bangladesh. Another 83 species sequenced were not previously recorded for the country, and include about 30 undescribed or potentially undescribed species. Several of the taxa that we could not sample represent erroneous records for the country, or sporadic occurrences. Species identifications were classified at confidence levels 1(best) to 3 (worst). We propose the new term Operational Barcode Unit (OBU) to simplify references to would-be DNA barcode sequences and sequence clusters. We found one case where there were two mitochondrial lineages present in the same species, several cases of cryptic species, one case of introgression, one species yielding a pseudogene to standard barcoding primers, and several cases of taxonomic uncertainty and need for taxonomic revision. Large scale national level DNA barcode prospecting in high diversity regions may suffer from lack of taxonomic expertise that cripples the result. Consequently, DNA barcoding should be performed in the context of taxonomic revision, and have a defined, competent end-user.

Could do better! A high school market survey of fish labelling in Sydney, Australia, using DNA barcodes

Background

Processed seafood products are not readily identifiable based on physical characteristics, which leaves the industry vulnerable to high levels of product mislabelling (globally estimated at 5–30% mislabelled). This is both a food safety issue and a consumer protection issue as cheaper species could be substituted for more expensive species. DNA barcoding is proving to be a valuable tool for authentication of fish products. We worked with high school students to perform a market survey and subsequent species assessment via DNA barcoding to investigate the accuracy of fish product names used by retailers in Sydney, Australia.

Methods

Sixty-eight fish samples, sold under 50 different common names, were purchased anonymously from two retailers in Sydney. Each product name was recorded and reconciled with the Australian Fish Names Standard (AFNS). Samples were DNA barcoded and resulting sequences were deposited in the online Barcode of Life Data system using the simplified Student Data Portal interface.

Results

Forty percent of the fish names did not comply with the AFNS, however, half of these were either spelling errors or vendors supplied more information than the standard requires. The other half of the non-compliant samples were given common names not listed on the AFNS. Despite this lack of standardization, DNA barcode data confirmed the retailers’ identifications for 93% of samples and 90% of species sampled.

Discussion

The level of mislabelling we report for Sydney retailers (7% of samples or 10% of species) compares favorably with the global rates of 5–30%, but unfavorably with the only previous DNA barcode fish authentication study for Australia, which found no confirmed mislabelling in Hobart. Our study sampled mostly Australian produce, only two retailers and no restaurants. Results of our limited sample suggest that although many Sydney fish retailers attempt to implement the voluntary fish name standards, the standards are inadequate. As Australia imports 75% of its seafood, and in other countries restaurants generally show lower levels of compliance than retailers, broader surveys are needed before generalizing these results. DNA barcoding is a powerful yet simple method supported by accessible online analytical tools. Incorporation of fish barcoding into high school science classes provided students with valuable firsthand experience in scientific research and drew together different strands of the NSW curriculum relating to genetics and sustainability. Given the techniques, equipment, and reagents are now readily accessible, we expect to see greater uptake of DNA barcoding technology by high schools, citizen scientists and consumer groups in Australia in future. However, there remains much scope for further development of DNA barcode diagnostics (both data and analytical methods) for commercial fish species.

Overview on Untargeted Methods to Combat Food Frauds: A Focus on Fishery Products

Authenticity and traceability of food products are of primary importance at all levels of the production process, from raw materials to finished products. Authentication is also a key aspect for accurate labeling of food, which is required to help consumers in selecting appropriate types of food products. With the aim of guaranteeing the authenticity of foods, various methodological approaches have been devised over the past years, mainly based on either targeted or untargeted analyses. In this review, a brief overview of current analytical methods tailored to authenticity studies, with special regard to fishery products, is provided. Focus is placed on untargeted methods that are attracting the interest of the analytical community thanks to their rapidity and high throughput; such methods enable a fast collection of “fingerprinting signals” referred to each authentic food, subsequently stored into large database for the construction of specific information repositories. In the present case, methods capable of detecting fish adulteration/substitution and involving sensory, physicochemical, DNA-based, chromatographic, and spectroscopic measurements, combined with chemometric tools, are illustrated and commented on.