As part of the Labelfish Project’s work to broaden interest in, and deepen the knowledge of, stakeholders in seafood labelling, traceability and molecular techniques, please find below some brief reviews of papers in the area. These papers are salient works in terms of their recency or their importance to the area of conservation genetics.
Moore J.C., Spink J., Lipp M. (2012). Development and application of a database of food ingredient fraud and economically motivated adulteration from 1980 to 2010. Journal of Food Science, 77 (4): R118-R126.
This paper describes the development and application of a database (USP Food Fraud Database) of food ingredient fraud issues from publicly available references (articles in scholarly journal and general media) from 1980 to 2010. The database described in this paper will be published in the US Pharmacopeial Convention’s Food Chemicals Codex, 9th edition inMarch 2014 (http://www.usp.org/store/products-services/food-chemicals-codex-fcc). The collected information from the articles are organized into a database (this database contains today more than 2000 entries) which permits to review and analyse the data to identify trends.
Olive oil, milk, honey, and saffron are the most commonly adultered food products reported in the scholarly journals, and the HPLC and infrared spectroscopy are the most common alaytical detection methods with the chemometrics data analysis. The authors of this paper indicate that the database will provide baseline information and data useful to governments, agencies and companies to assess the risks of specific food products. Future expansion of the database will include articles published before 1980, articles in other language than English and data from outside the public domain.
On 8 October 2013, following the scandal of horse meat, the Committee on the Environment, Public Health and Food Safety of the Eurepean Parliament / Legislative Observatory has published a report on food fraud and control, including a statement of reasons and proposals resolution of the European Parliament. This report concerning cases of adulteration, substitution, alteration or counterfeiting worldwide is mainly based on this paper.
The report could be downloaded at http://www.europarl.europa.eu/sides/getDoc.do?pubRef=-//EP//NONSGML+COMPARL+PE-519.759+02+DOC+PDF+V0//EN&language=EN.
In this report, fish is 2nd in the top 10 products that are most at risk of food fraud.
Rehbein. H., Schiefenhövel, K., 2012. Evaluation of a rapid PCR-based method for species identification of raw and processed fish and shrimps. Journal of Aquatic Food Product Technology, 21, 86-96.
This paper describes a rapid deoxyribonucleic acid (DNA) extraction and amplification method to identify raw and processed fish and shrimp using polymerase chain reaction (PCR)-based techniques. The KAPA Express Extract Kit delivered DNA from raw, cooked, canned, and marinated products that were suitable for mutation detection. Segments of mitochondrial genes, sized from 123 to 464 base pairs (bp), were amplified by PCR kits from two vendors. Amplicons of raw fish fillets were differentiated by single strand conformation polymorphism (SSCP) analysis, raw or cooked shrimps were analyzed by restriction fragment length polymorphism (RFLP), and the PCR product obtained for marinated herring was sequenced. The extracted DNA was not degraded during storage in the refrigerator for about 1 week or in the freezer-cabinet for 1 month. The authors conclude that in many cases lengthy procedures for isolation of DNA are not necessary for species identification of fishery products by PCR and propose the following kits to be used directly for PCR: KAPA Express Extract (KAPA BIOSYSTEMS, Woburn, MA, USA); Phire®Animal Tissue Direct PCR kit (New England Biolabsm Fk/Main, Germany) and Fast Tissue-to-PCR kit (Fermentas, St. Leon-Rot, Germany).
De Battisti, C., Marciano, S., Magnabosco, C., Busato, S., Arcangeli G. & Cattoli, G., 2014. Pyrosequencing as a tool for rapid fish species identification and commercial fraud detection. Journal of Agricultural and Food Chemistry, 62 (1), pp 198–205.
This paper looks at the potential of using a novel DNA-based sequencing technique called pyrosequencing for species identification. This technique works by using short stretches of nucleotides (approximately 30-40 nucleotides) downstream from a sequencing primer, which sequences the nucleotides accurately and efficiently. 116 specimens from the orders Pleuronectiformes and Clupiformes were collected. These included, fresh, frozen and processed specimens. After DNA extraction the samples were subjected to a preliminary species identification using cytochrome c oxidase I (COI) sequencing. Sequences of conserved regions of mtDNA from different fish species in GenBank were aligned using specific software. From this data, a set of PCR primers and a sequencing primer were designed. The PCR products were then biotynylated to allow purification and selection of the fragment in the pyrosequencing procedure. The identification of samples was split into two parts: one PCR reaction targeting the 16S rRNA gene followed by pyrosequencing, which identified 20 species, followed by a further two PCR amplifications and pyrosequencing, which identified the remaining five species.
All samples were correctly identified using this method, which shows it works as well on processed fish products as on fresh specimens. The authors claim that the entire process can be completed in 3.5 hours if all three PCR reactions are carried out at the same time. The cost per sample of pyrosequencing is €5 – €6, compared with the more expensive Sanger method which costs €11 – €12 per sample.
Velasco, A., Sánchez, A., Martínez, I., Santaclara, F.J., Pérez-Martín, R.I., Sotelo, C.G., 2013. Development of a Real-Time PCR method for the identification of Atlantic mackerel (Scomber scombrus). Food Chemistry ,141: 2006-2010.
The work provides a new methodology for Atlantic mackerel species identification, based on Taqman technology. It provides a fast and comparatively inexpensive method to unequivocally identify Scomber scombrus species in both unprocessed and manufactured fish products.
A set of specific primers and a Minor Groove Binding (MGB) TaqMan probe based on sequences of the mitochondrial cytochrome b region was designed to authenticate Scomber scombrus among other possible substitute species, using Real Time-PCR.
Specificity and cross-reactivity was tested with 45 samples from 30 species, giving no false positives.
This method was also tested with 36 reference samples and 19 commercial samples of Scomber scombrus with different types of processing, giving a 100% of positive results.
This method is attainable by most laboratories, and it does not require neither reference sequences databases nor great quality DNA. Other advantages are its reliability, sensitivity and specificity, and it is also quicker and cheaper than other authentication methods for Scomber scombrus
Armani, A., Castigliego, L., Tinacci, L., Gandini, G., Gianfaldoni, D., Guidi, A., 2012. A rapid PCR-RFLP method for the identification of Lophius species. Eur Food Res Technol, 235: 253-263
In order to meet the potential substitution of high valued fish species as L. piscatorius and L. budegassa by other low prized fish a new cost-effective and rapid PCR-RFLP system with a specific primer pair was developed for authentication of the seven Lophiu sspecies. To design the specific primer pair LOP1for and LOP6rev the complete sequence of cytochrome b of 35 fresh and frozen Lophius species purchased from trustable resources were analyzed and aligned with other 20 references retrieved from Genbank. The new specific primer pair enabled the amplification of a 566 bp fragment only from anglerfish. No amplification with other fish species that may be used as a substitute for filets of Lophius spp. was observed. In addition the RFLP system carried out by means of the enzyme BFAI generates specific fragments for the seven Lophius species. For testing the applicability of this system 75 fresh and frozen specimens of the seven anglerfish species were analyzed. Only in one case the authors found a haplotype in a specimen of L. budegassa that shows other fragment patterns than normally L. budegassa species shows. Nevertheless, the investigation of48 commercial market fish products labelled as anglerfish demonstrates that the developed PCR-RFLP method provides in comparison to FINS analysis in all cases correct results.