New Fish on the German Market: Consumer Protection against Fraud by Identification of Species

Abstract

Protein-and DNA-based methods have been developed to identify fish species recently introduced into the German market. By means of isoelectric focusing (IEF) of sarcoplasmic proteins, characteristic protein patterns were obtained for pangasius (P. hypophthalmus), yellow fin sole (Limanda aspera) and arrowtooth flounder (Atheresthes stomias).In case of pangasius and yellow fin sole a~460 base pair segment of the cytochrome b gene was amplified by PCR and sequenced. Restriction fragment length polymorphism (RFLP)-and single strand conformation polymorphism (SSCP)-analysis of three genes (cytochrome b, immunoglobulin heavy chain constant region, trypsinogen) demonstrated the possibilities of rapid identification of P. hypophthalmus.Zusammenfassung: (Verbraucherschutz durch Bestimmung der Fischart in Erzeugnissen am Beispiel neuer Fischarten auf dem deutschen Markt) Protein-und DNA-basierte Nachweismethoden sind entwickelt worden, um Fisch-Spezies identifizieren zu können, die kürzlich in Deutschland in den Handel gelangt sind. Mit Hilfe der Isoelektrofokussierung von sarcoplasmatischen Proteinen wurden die typischen ProteinbandenMuster für Pangasius hypophthalmus, Limanda aspera und Atheresthes stomias erstellt.Für P. hypophthalmus und L. aspera wurde ein etwa 460 Basenpaare umfassender Abschnitt des Cytochrom b-Gens mittels PCR amplifiziert und sequenziert. Die RFLP-und SSCP-Analyse von drei bestimmten Genen lassen eine schnelle Identifizierung von P. hypophthalmus zu.

Authentication of closely related scombrid, catfish and tilapia species by PCR-based analysis and isoelectric focusing of parvalbumin

“…5a, C. batrachus, H. capitulum and P. hypophthalmus (those species, for which light muscle was available) expressed characteristic protein patterns; intra-species variability occurred only for H. capitulum. This result is in accordance with an earlier study on the identification of P. hypophthalmus, C. gariepinus and Siluris glanis by IEF [57], which demonstrated that IEF is a fast and reliable identification method for raw catfish fillets. The patterns of Nile tilapia (O. niloticus) and red tilapia (Oreochromis spp.)…”

“…In European and North American restaurants, tra fish (Pangasius, P. hypophtalmus) have often been sold under the label of snapper, tuna or sole [57,74].…”

“…Information on this allergen has been recently reported for tuna [49][50][51][52][53], but knowledge of parvalbumin genes and their expression in tilapia and snapper is limited [54][55][56]. IEF of sarcoplasmic proteins has been applied to identify P. hypophthalmus, P. bocourti [57] and other catfish species [58]. Snappers have been included in this study, as these species have often been involved in the substitution of high-priced fish with cheaper species, such as pangasius and tilapia in fish restaurants [15].…”

The Influence of Changes in the Market Environment on Economic Production Characteristics of Pangasius Farming in the Mekong Delta (Vietnam)

“…figure 3). Factors that contributed to the recent success of pangasius farming in the MD include (see also Khoi (2009) andBinh (2009)): i) the development of modern production and control systems ensuring that international standards for food safety and hygiene could be met (Orban et al 2008); ii) the specific characteristics of the fish species in terms of flavour, colour, and low cholesterol content, which ensured a high demand (Orban et al 2008); iii) low production costs, which allowed farmers to keep prices low (Rehbein 2008); and iv) improvements in the production chain, such as the introduction of the fingerling socialisation programme, which created a more reliable source of tra and basa fingerlings. Table 1 shows that Vietnamese exporters responded very quickly to the challenge of the Catfish War with the US and successfully entered new markets.…”

Substitution of high-priced fish with low-priced species: Adulteration of common sole in German restaurants

“…High exploitation levels (Oceana, 2013) and increased worldwide consumption of common sole have resulted in a shortage of supply and increasing prices (Herrero et al, 2012;Rehbein, 2008) which is also true for a lot of other North Atlantic flatfish species ). In the last years fish from other seas (e.g.…”