fish species identification (7)

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Fish species identification is normally undertaken using DNA barcoding methods. However, it is often useful to have an on-site rapid non-destructive method to verify fish species. In this study, 2 Raman spectrometers (a portable Raman spectrometer and a benchtop confocal Raman spectrometer) were used and compared for their performance to identify 11 species of fish (4 species of Salmonidae and 7 species of non-Salmonidae).  Supervised chemometric/machine learning classification models were constructed based on a hierarchical classification principle to develop this 11-class identification. Both Raman spectrometers were able to differentiate Salmonidae from non-Salmonidae fish with close to 100% accuracy. To further identify the fish to species level, the portable Raman spectrometer provided better accuracy (i.e., 93% and 93% accuracy for the Salmonidae group and non-Salmonidae identification, respectively) compared to the benchtop Raman spectrometer (i.e., 90% and 84% accuracy for the Salmonidae group and non-Salmonidae identification, respectively). The overall non-destructive analytical time was only 5 minutes.

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Seafood species substitution is one of the most common types of fraud.This study aims to develop new assays based on DNA to identify fresh mackerel (Scomber spp.) and mackerel species in canned products. Primers were designed to identify a DNA mini-barcoding region suitable for species identification of 4 commercial mackerel species Scomber scombrus,Scomber japonicus,Scomber colias, and scomber australaticus in processed products. Also a new assay based on RPA coupled with the lateral flow visualisation was developed for the identification of the most expensive species of fresh mackerel (Scomber scombrus).  

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Species substitution of seafood is a major global problem. German scientists have developed a rapid, easy to use, DNA microarray for fish species identification based on cytochrome b and 16S rDNA probes. The microarray test takes only 4-5 hours to complete, and identifies ten important commercial fish species. The microarray was validated using 67 authentic fish species, and was able to clearly identify the 10 species even from closely related species of fish.

1076187540?profile=RESIZE_710x Read the abstract here

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German researchers have developed and undertaken an in-house validation of an LC-MS and LC-MS/MS-based assay for authenticity testing of certain fish species. An enzyme digest and trypsin hydrolysis of freeze dried samples of commercially available Lutjanus malabaricus (red snapper) and Sebastes spp. (redfish) were analysed by LC-electrospray-MS and MS/MS assay with multivariate analysis, which enabled the two species to be  distinguished from each other. An additional 68 samples [nine additional marine species such as pangasius (Pangasianodon hypophthalmus), salmon (Salmo salar), turbot (Scophthalmus maximus), plaice (Pleuronectes platessa), sole (Solea solea), lemon sole (Glyptocephalus cynoglossus), halibut (Reinhardtius hypoglossoides), red salmon (Oncorhynchus nerka), and great scallop (Pecten jacobaeus)] served as blinded negative controls to ensure the specificity of the assay. 

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In this article, untargeted methods capable determining the authenticity of foods are reviewed. The article also reviews and discusses a more specific focus on methods for detecting fish adulteration/substitution and involving sensory, physicochemical, DNA-based, chromatographic and spectroscopic measurements, combined with chemometric tools.
                      Read the full review at: untargeted methods for fish

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JRC (the EU Commission's Joint Research Centre) has just published a report summarising 20 years of EU funded projects on the development of emerging technologies to identify fish species and improve fish trade traceability. The report covers methods based on DNA amplification, DNA sequencing, DNA arrays, proteomics and chemical profiling.

Read the report at: JRC fish species report

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This paper records the outcome of the latest and largest multi-species, transnational survey of fish labelling to date, which demonstrates an apparent reduction of seafood mislabelling in Europe. The authors argue that recent efforts in legislation, governance, and outreach have had a positive impact on industry regulation coupled with successful molecular biology methodology.

Read more at: http://usir.salford.ac.uk/37241/1/Mariani%20et%20al_Final-FEE-Dec2015.pdf

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