S3Food is a European funded initiative to bring digital innovation to the agrifood sector. One of the projects based in Greece, combines DNA profiles of the olives and the EVOO into the blockchain system. Other quality parameters such geographical location, yield, harvesting and milling time and other quality parameters are also entered into the blockchain information system. This is designed to ensure that there is (non-tampering) full traceability from olive grove to shelf, and hence assure the integrity of the olive oil along the supply chain from farm to fork. The whole traceability story will be available to consumers by means of a QR code.
Rice is one othe most consumed foods globally, and different subgroups of rice varieties have different sales values e.g. Basmati rice is much more expensive than non-Basmati long grained rice. This paper by Portuguese researchers reviews DNA-based methods because they are considered particularly reliable and stable for discrimination of rice varieties. The review covers the diversity of strategies and ongoing improvements already tested, highlighting important advantages and disadvantages in terms of costs, reliability, labour-effort and potential scalability for routine fraud detection.
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Seafood has been identified as one of the foods vulnerable to mislabelling and fraud. In addition, Singapore has a high consumption of seafood (average 22kg/per capita/year). Researchers at the National University of Singapore conducted a survey to verify the labelling/description of seafood species. Eighty eight samples were collected from retail outlets and restaurants. Using mitochondrial DNA barcoding of the cytochrome c oxidase Subunit-I to identify seafood species, 42 different species were identified. In total, 26% (23) of the samples were mislabelled. The three most frequently mislabelled fish were Anoplopoma fimbria (Sablefish) sold as Black Cod, Dissostichus eleginoides (Patagonian toothfish) sold as Cod or Seabass, and Pangasianodon hypophthalmus (Iridescent shark) sold as Dory or Bocourti. Restaurants did not show any evidence of mislabelling, and all the mislabelled samples came from retail outlets.
Herbs are high value ingredients, which are vulnerable to adulteration and fraud. Confirmatory methods based on DNA analysis have shown to be the most useful in investigating herb adulteration. In this study, a customised database and bioinformatics pipeline was developed based on a DNA barcoding metagenomics approach to herbal species identification. The pipeline performance was tested with publicly available datasets, as well as, newly sequenced herbal plants and products. The usefulness of metagenomics is limited by the availability of reference sequences and the need for sequencing depth. However, this method shows promise for evaluating the authenticity of different herbal products provided that it is further refined to increase the qualitative and quantitative accuracy.
You can read tihe full open access paper.
Chilean researchers have carried out a survey of misdescription and fraud in the sale of swordfish (Xiphias gladius) in Santiago's fish and open-air markets. DNA barcoding was used for taxonomic identification of swordfish and shark species. Forty seven headless, gutted and fin-removed samples sold as swordfish were collected from the fish and open-air markets. Most of the samples (91.5%) were correctly described as swordfish, but 6.4% were identified as porbeagle shark (Lamna nasus) and 2.1% as shortfin mako (Isurus oxyrinchus). No substitution was found in supermarket samples. These shark species are classified as vulnerable and endangered (IUCN), respectively, and listed in Appendix II (CITES). The authors have recommended stronger fish labelling rules and enforcement in Chile to improve shark conservation.
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In the last decades, the demand for molecular tools for authenticating and tracing agri-food products has significantly increased. Food safety and quality have gained an increased interest for consumers, producers, and retailers, therefore, the availability of analytical methods for the determination of food authenticity and the detection of major adulterations takes on a fundamental role.
Among the different molecular approaches, some techniques such as the molecular markers-based methods are well established, while some innovative approaches such as isothermal amplificationbased methods and DNA metabarcoding have only recently found application in the agri-food sector.
In this review, we provide an overview of the most widely used molecular techniques for fresh and processed agri-food authentication and traceability, showing their recent advances and applications and discussing their main advantages and limitations. The application of these techniques to agrifood traceability and authentication can contribute a great deal to the reassurance of consumers in terms of transparency and food safety and may allow producers and retailers to adequately promote their products.
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A Ph.D thesis from the University of Milan-Bicocca in English is publicly available. The thesis gives a good overview of DNA barcoding, NGS (Next Generation Sequencing) and metabarcoding, and isothermal nucleic acid amplification. The research carried out looked at applying DNA barcoding to processed foods, which required smaller DNA fragments. However, the approach is not suitable for mixed species samples, and NGS and metabarcoding approaches were more successful. Finally, an isothermal amplification assay was applied to authenticate truffles.
You can read the 253 page thesis here
Sanger sequencing (DNA barcoding) is a robust method for species identification. However, it is not always suitable for species identification of processd mixed species products. Chinese researchers have developed an NGS method based on the amplification and sequencing of shorter 16S rRNA DNA sequences. The assay was developed using a mixture of 8 salmon species, which were all correctly identified even when the species was presented as low as 1%(w/w). It was tested with a market survey of 32 commercial salmon products. Sanger sequencing was used on single species unprocessed products and NGS on mixed species products, which was also cross validated with a real-time PCR assay. The survey revealed that 50% of the samples were mislabelled.
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This study used DNA barcoding to identify fish species and microbiome profiling to study the presence of pathogens. Between February 2018 and October 2020, 127 fish samples were collected from restaurants (83 samples), and the remainder (44 samples) from hypermarkets, supermarkets, markets, seafood wholesalers/retailers, and fishing harbours. The microbiological analysis was undertaken because most of the restaurant samples were raw fish sashimi/sushi. The study found that 24 of the samples were mislabelled as regards the fish species, and snapper had the largest number of mislabelled samples (11), which had been substituted by tilapia. This may be due to the labelling of tilapia as Taiwan-Snapper.
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Fish species substitution and/or mislabelling is known to be a serious global issue. Spanish researchers used DNA barcoding to identify fish species in 313 samples collected in 204 mass catering outlets from 15 Spanish Autonomous Communities. The results showed that 50% of the food catering establishments sold mislabelled seafood. The fish species found to be most substituted were dusky grouper (shown left and known as Mero in Spanish) and tope shark, which were substituted by similar species of fish from Asian, South American and South African regions.
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In a follow up of a 2018 report, Oceana Canada have released a recent report on the results of a survey of 90 samples taken from 50 different locations in Montreal in 2019. The samples were sent to a commercial laboratory for testing using DNA barcoding for species identification, which found that 31 samples were a different species than was claimed, 21 were mislabelled and three contained species not authorised for sale in Canada. The 2018 report found a mislabelling rate of 44% in samples from from 5 cities, excluding Montreal. The Montreal results, when combined with previous investigations since 2017, found 47% of the 472 fish samples to date were mislabelled in Montreal, Victoria, Vancouver, Toronto, Ottawa and Halifax.
Researchers from the University of Guelph in collaboration with the Canadian Food Inspection Agency (CFIA) have found high levels of fish mislabelling in the supply chain starting from imports and increasing as the supply moves along the chain to retail. The research team examined 203 samples from 12 key targeted species collected from various importers (23% of samples), processing plants (5.5%) and retailers (69.5%) in Ontario. The species of fish was identified in the samples using DNA barcoding. The results revealed that overall 32% of the 203 samples were mislabelled, with 17.6 % mislabelling at the import stage, 27.3% at processing plants and 38.1% at retailers. The authors commented that the higher mislabelling rate in samples collected from retailers, compared to that for samples collected from importers, indicates the role of distribution and repackaging in seafood mislabeling. Also, there is a lack of harmonisation in the regulatory framework between for example, Canada and the US, where there is a lack of equivalence in the commercial names given to fish species. This would be improved by giving the scientific name as well.
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Many shark populations are in decline, primarily due to overexploitation. In response, conservation measures have been applied at differing scales, often severely restricting sales of declining species. Between February 2016 and November 2017, scientists at the University of Exeter analysed a total of 117 samples of shark meat products collected from 90 different caterers/retailers. Seventy eight of these were battered and fried originating from fish and chip takeaways, and 39 were either fresh or frozen and collected from fishmongers. In addition, 10 fins collected from an Asian food wholesaler, as well as 30 fins seized by the UK Border Force on their way from Mozambique to Asia were also analysed. Using multiple extraction techniques and DNA barcoding, the species of shark in the samples were identified. As regards the fish and chip takeaways, the majority of samples were identified as spiny dogfish (Squalus acanthias), which is critically endangered in the Northeast Atlantic and landings have been prohibited. The fin samples included scalloped hammerhead sharks (Sphyrna lewini), which are endangered globally and subject to trade restrictions, and other threatened sharks such as shortfin mako and smalleye hammerhead sharks.
The New York Attorney General's Office has just published a report of a survey into the labelling of fish species in New York's supermarket chains. Fish (snapper, grouper, cod, wild salmon, halibut, sole, striped bass and white tuna) was sampled from 155 retail locations from 29 supermarket chains, and sent to Northeastern University for DNA testing. 27% of the samples were found to be mislabelled. A group of 5 of the supermarket chains were responsible for most of the mislabelled samples with more than 50% of their samples mislabelled. 87.5% of the lemon sole, and 67% of the red snapper were mislabelled, and 28% of the salmon was wrongly sold as wild when it was farmed. The report gives best practice for businesses to ensure that the consumer is not purchasing mislabelled fish.
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