New genetic technique to identify wrongly labelled foods

A new technique known as DNA barcoding has been used by researchers at Sackler Institute for Comparative Genomics at the American Museum of Natural History to identify fish in New York sushi bars which have been wrongly labelled/sold. A quarter of what was labeled as tuna on sushi menus was bluefin, and some was even escolar, a waxy, buttery fish often labelled 'white tuna' that is banned for sale in Japan and Italy because it can cause gastrointestinal distress.

Using a short sequence of mitochondrial DNA from the cytochrome c oxidase subunit 1 gene, or "cox1," to identify a species, this tool has, among other results, identified the presence of endangered whales in Asian markets, looked at the species of ungulates appearing in African bushmeat markets, and documented fraud in the labeling of caviar and red snapper.

Lowenstein and colleagues used DNA barcoding to identify the kind of fishes labeled 'tuna' in one Denver and 30 New York City restaurants. Almost half of the restaurants did not accurately label the kind of tuna sold, and only 14 of the samples used for this study were listed on the menu by a specific name like bigeye tuna, albacore, or bluefin.

Bluefin are three species of large, fast-moving, high-energy tuna that can cover enormous distances in the ocean. While this is obviously of major importance in fish conservation work, it also has implications for allergics wishing to be sure that they are not being fed potential allergens which have been wrongly labelled.

‘In conservation, the ability to identify species in trade is a prerequisite for CITES (Convention on International Trade in Endangered Species) listing, and this research confirms that this requirement can be met,’ says George Amato, Director of the Sackler Institute. ‘The long-term application of barcoding is the development of a hand-held identification device that anyone can use, so that wildlife management teams can seamlessly and efficiently identify a species and maybe the geographic origin of specific samples.'

Such a device would also be extremely relevant for food allergics.

The new research is published in PLoS One.

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First Published in November 2009


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