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By Natalie Abram
Aquatic Science Editor
Next time you check out a sushi menu, the “crab meat” could be a fake. Fortunately, aquatic food technology has elevated both the preparation and identification of sushi. Sushi is very popular. Real sushi is specific seafood that is prepared raw, cooked or marinated, with seaweed or vegetables. The fish are precisely prepared to only include the edible parts. Itamae, or special sushi chefs, undergo rigorous techniques to butcher the fish precisely and remove any bones, scales and organs.
What fish are you consuming?
When sushi is wrapped in a roll, or fried tempura-style, the common identifiers like morphology, coloring, and size cannot be determined. This makes “knock-off sushi” somewhat easy to disguise, and is more common. Some seafood gets mislabeled on menus as specific and more expensive sought-after varieties, but is actually cheaper or “trash” fish. Many scientists and amateurs alike are hitting the restaurants, markets and harbors for fish samples, and test using molecular forensics. During some incognito fish sampling in New York City several years ago, a halibut turned out to be a mackerel, and a prized tuna was found to be tilapia. Another popular farce is the highly expensive Caspian sturgeon caviar eggs, which have been swapped for lowly Mississippi paddlefish eggs.
Biotechnology has increasingly become more accessible and cheaper to run genome or DNA sequencing comparisons. DNA analysis and barcoding has been the most efficient way to identify the fish at a taxonomic level. “A piece of tuna sushi has the potential to be [either] an endangered species, a fraud, or a health hazard” (Lowenstein). Two major databases, called GenBank and Barcode of Life Data Systems, have thousands of genomes on file from which to compare. Additional techniques such as PCR, COI, and BLAST have also been utilized to make assessments.
Why should they be tested?
The authentication of seafood is critical for not only the consumers purchasing the food, but also for fishery managers to conserve endangered species. This awareness will hopefully aid consumers in making responsible choices and asking questions at their local sushi stands.
Abdullah A, Rehbein H. Authentication of raw and processed tuna from Indonesian markets using DNA barcoding, nuclear gene and character-based approach. European Food Research and Technology = Zeitschrift für Lebensmittel-Untersuchung und -Forschung.A. 2014; 239(4):695-706.
Aquatic Science & Fisheries Abstracts (ASFA) 1: Biological Sciences & Living Resources (1971 - current)
Feuer A. Fish posing as other fish? Not in this restaurant. New York Times (1923-Current file). Aug 23 2008:2.
Lowenstein JH, Amato G, Kolokotronis S. The real maccoyii: Identifying tuna sushi with DNA barcodes - contrasting characteristic attributes and genetic distances. PLoS One. 2009; 4(11).
Ku, Robert Ji-Song. Glossary of Food Terms. Food in Asia and the Pacific: Dubious Gastronomy: The Cultural Politics of Eating Asian in the USA. Hawaii: University of Hawaiʻi Press, 2014. Ebrary Ebook.
Oceanic Abstracts (1981 - current)
Wong LL. DNA barcoding and related molecular markers for fish species authentication, phylogenetic assessment and population studies. [Order No. 3497539]. Auburn University; 2011.