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DNA Bar Coding Finds Mislabeled Sushi
Hugh Pickens writes "The NY Times reports that Kate Stoeckle and Louisa Strauss, who graduated this year from the Trinity School in Manhattan, took on a freelance science project to check 60 samples of seafood using a simplified genetic fingerprinting technique called DNA Bar Coding to see whether the fish New Yorkers buy is what they think they are getting, and found that one-fourth of the fish samples with identifiable DNA were mislabeled: A piece of sushi sold as the luxury treat white tuna turned out to be Mozambique tilapia, a much cheaper fish that is often raised by farming. Roe supposedly from flying fish was actually from smelt." (More below.)
"Seven of nine samples that were called red snapper were mislabeled, and they turned out to be anything from Atlantic cod to Acadian redfish, an endangered species. The project began over dinner with Stoeckle's father, a scientist and early proponent of the use of DNA bar codings. Instead of sequencing the entire genome, bar coders examine a single gene. Dr. Stoeckle said he was excited to see the technology used in a new way and compared the technique to GPS. 'The smaller and cheaper you make something,' he said, 'the more uses it has.'"
Here in Tampa, Florida area, this was recently a very big deal. One of the things Tampa is famous for is Grouper, and several well-known restaurants were found to be serving cheaper fish instead of Grouper.
6 out of 11 restaurants served cheaper fish.
According to that article though it's hard to tell whether the deception was intentional, and even if so, who was deceptive: the restaurant, the wholesaler, etc.
Steve Palumbi did this back in the mid-90's for whale and dolphin products being sold in commercial markets in Korea and Japan (Baker and Palumbi 1994 Science 265: 1538; Baker et al. 1995 Molecular Ecology 5:671). Essentially they went around the fish stalls taking samples and amplifying and sequencing them in their hotel room. From the latter article abstract:
This 'spot check' revealed a surprising variety of species for sale, including minke, fin and humpback whales and one or two species of dolphins sold as 'kujira' or whale. In the Korean survey, DNA amplifications were conducted by two of us (C.S.B. and F.C.) working with independent equipment and reagents. The two sets of DNA amplifications were returned to our respective laboratories and sequenced independently for cross-validation. Among the total of 17 species-specific sequences we found a dolphin, a beaked whale, 13 Northern Hemisphere minke whales (representing at least seven distinct individuals) and two whales which are closely related to the recognized sei and Bryde's whales but could not be identified as either using available type sequences. We suggest that these two specimens represent a currently unrecognized species or subspecies of Bryde's whale, possibly the so-called 'small-form' reported from the tropical waters of the Indo-Pacific.
Until these guys went out and actually did the sequencing, no one knew for sure how much illegal whaling activity was going on.
In Japanese cuisine, sushi is vinegared rice, usually topped with other ingredients, including fish, various meats, and vegetables.
Outside of Japan, sushi is sometimes misunderstood to mean the raw fish itself, or even any fresh raw-seafood dishes.
In Japan, sliced raw fish alone is called sashimi and is distinct from sushi, as sashimi is the raw fish component, not the rice component.
The word sushi itself comes from an archaic grammatical form of a word that is no longer used in other contexts; literally, sushi means "it's sour".
Technically, raw fish is "sashimi", but is often combined with rice and seaweed and other ingredients to make sushi. Not all sushi contains sashimi, but most does. I don't think rice by itself counts as sushi.
I work as a fish wholesaler. We deal mostly with restaurants but we do a few retail establishments too.
The fish business is surprisingly crooked. With the Russian mafia controlling the caviar trade and various fly by night operations selling foul product that has been color treated to look new.Having a competent chef is vary important when dealing with fish quality. Labeling is a constant problem in the fishing industry even with the COOL act. Domestic red snapper is the worst of the lot when it comes to company's labeling poorly. Mainly because on a wholesale level the fish sells for 13.95-14.95 per pound fillet (regional price only), while tilapia is often sold at 6.95-7.95 per pound fillet. Other things that get sold as red snapper is red rock, corvina, lane snapper, ling snapper. (although ling is often not cheaper) It is so bad that the USDC stepped in and only 1 genus of fish can be sold as red snapper, 2 in California. The trick to buying red snapper is to only buy it skin on, preferably whole. If it is skin off fillet pass because it's almost impossible to identify then. Selling tilapia as tuna is retarded those two fish do not even taste similar although if the fish is drenched in soy sauce and wasabi it is difficult to tell even the widest of gaps in fish taste.
Also since this is going to come up at one point. Scallops that are marked sea scallops or processed scallops ARE NOT skate or shark. These scallops are treated with tripolyphosphate so they soak up water. Dry pack scallops are not treated so they are a better quality scallop. It is very difficult to cut skate in such a way on an industrial level to make it look like a scallop especially when the yield from it would cut into profit and most chefs can tell the difference.
And while I'm at it:
Amberjack is not mahi
Ahi meens tuna or yellowfin tuna. Saying ahi tuna is silly
Ono and wahoo are the same god damn fish just buy the cheaper wahoo
Langostino is from a squat lobster which isn't really a lobster but it still tastes good.
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The same thing happened to orange roughy and monkfish (both some of the most hideous looking fish you'll ever see), and shark (difficult to prepare because of the high ammonia content in the meat). All were once considered trash and literally shoveled overboard in the pursuit of (at the time) more valuable fish. Now that those more valuable fish have been overfished, the industry spruces up the image of what was formerly considered trash fish to sell to the public.
BTW, what's sold as red snapper often isn't red snapper. Pretty much any of the snappers and frequently any of the rockfishes (aka rock cod) are sold as red snapper. Most of their meat is pretty similar, but there are subtle differences.