by Marion Nestle
May 6 2012

Tuna scrape: a case study in international food safety

My Q and A column in the San Francisco Chronicle appears on the first Sunday of every month.  This one is about safety problems with tuna scrape.

Q: I had no idea that the tuna in my sushi roll was scraped off the bones in India, ground up, frozen, and shipped to California. Is this another “slime” product? Can I eat it raw?

A: No sooner did the furor over lean, finely textured beef (a.k.a. “pink slime”) die down than we have another one over sushi tuna. On April 13, the Food and Drug Administration said Moon Marine USA, an importing company based in Cupertino, was voluntarily recalling 30 tons of frozen raw ground yellowfin tuna, packaged as Nakaochi scrape.

Centers for Disease Control and Prevention investigations linked consumption of Nakaochi scrape sushi to about 250 diagnosed cases and an estimated 6,000 or so undiagnosed cases of illness caused by two rare strains of salmonella. Among the victims who were interviewed, more than 80 percent said they ate spicy tuna sushi rolls purchased in grocery stores or restaurants.

Scrape refers to the meat left on fish skeletons after the filets are cut off. This is perfectly good fish, but difficult to get at. I once visited an Alaskan salmon packing plant and asked what happened to the delicious looking meat between the bones. The answer: pet food. (Lucky cats.)

A hot commodity

But tuna is too valuable to leave behind, and companies in India use special devices to scoop out the meat, combine it with scrapings from many other fish, chop the mixture, freeze it in blocks, and ship it to importers in the United States. Unlike “pink slime,” tuna scrape is not treated with ammonia or anything else to kill harmful bacteria.

Nevertheless, it is supposed to be safe. The FDA requires producers of imported foods to follow established safety plans. Although the United States imports about 80 percent of seafood sold domestically, the FDA only inspects 1 or 2 percent.

This means we have to rely on the diligence of international food producers in following safe-handling procedures, and of U.S. importers in verifying safety through pathogen testing. But even well-intentioned producers can make safety errors, especially when dealing with high-risk foods.

Tuna scrape is very high risk. Its supply chain is long, complicated and international, leaving many opportunities for contamination. And it is eaten raw.

This tuna scrape came from a single processing plant in India owned by Moon Marine International of Taiwan. Tuna are plentiful off the Indian coast, and the tuna processing industry is expanding rapidly. India has dozens, perhaps hundreds, of fish processing facilities, but most are relatively small and their number, size and geographical dispersion make monitoring difficult.

Safe handling issues

The frozen scrape blocks are supposed to be held at subzero temperatures throughout shipping. Even so, they pose a safety risk. They combine the scrapings from many fish. One contaminated scraping can contaminate the entire lot.

And subzero freezing may kill some salmonella, but large fractions can survive, remain viable, and multiply when the blocks are thawed.

Once the tuna scrape arrived in America, I’m guessing it was trucked to Cupertino and from there to retailers and distributors who further trucked them to restaurants and grocery stores. There, sushi chefs thawed the scrape and used it to make spicy tuna rolls.

Tuna scrape is used in supermarket-grade sushi, not the fancy stuff. Sushi used to be – and still is, in places – an art form requiring exceptional skills. In Japan, sushi chefs can train for as many as 10 years to learn how to recognize the freshest, safest and most delicious fish. Sushi served by such chefs is made to order. It is never pre-prepared. It can be breathtakingly expensive.

But in America, sushi has gone mainstream. You can find prepackaged sushi rolls at practically any supermarket or convenience store, at a cost equivalent to hamburger.

Cheap sushi is made with cheap ingredients – hence, Nakaochi scrape – by chefs with far less training. A typical certification program for sushi chefs in this country can be completed in two or three months. Some offer certification online. Although these programs address safe food-handling procedures, the training is necessarily superficial.

What are the odds?

Sushi aficionados argue that while raw fish is never perfectly safe, the safety odds are much better when the chef is well trained, and the fish are freshly caught and cut to order in front of you. By their standards, tuna scrape is suitable only for pet food, which is at least cooked to kill pathogens.

If anything, the tuna scrape outbreak teaches why it is so important to know where food comes from and how it is made. Caveat emptor.

Nutrition and public policy expert Marion Nestle answers readers’ questions in this monthly column written exclusively for The Chronicle. E-mail your questions to, with “Marion Nestle” in the subject line.

Addition, May 14Bill Marler reports that the FDA “483 Inspection Report” on the Indian tuna processing facility is now available.  Here are excerpts from the most revealing section:

Tanks used for storage of process waters have apparent visible debris, filth and microbiological contamination…There is no laboratory analysis for water used in ice manufacturing at the [redacted] facility to show the water used to make ice is potable…Apparent bird feces were observed on the ice manufacturing equipment at Moon Fishery; insects and filth were observed in and on the equipment…Tuna processed at your facility, which is consumed raw or cooked, comes in direct contact with water and ice.

  • Actually, my understanding is that one critical control point for “raw” sushi is to freeze it to kill fish parasites, which may be found in both wild-caught and farmed fish. However, as you note, freezing does not change the possibility of bacterial hazard.

  • Middle Seaman

    One basic question deals with the safety of the so called fresh fish one buys at the grocery store. Whole Foods’, for instance, prices for fish are way higher than your regional supermarket. Are the fish any safer? What about whole fish?

    Laxity of regulation enforcement seems to put in risk all food you don’t grow yourself or just about all food. What are we supposed to do, move to Germany?

  • Monica

    As someone who enjoys sushi, I’d like to know how to use this information to help me make safe and sustainable choices when ordering… Is it better to order sashimi? If not, what should I order? How do I tell if a sushi chef is properly trained? What are the everyday takeaways here, for those of us who can’t grow our own food and still want to be able to eat at restaurants in America? For now, I think I’ll just skip the spicy tuna rolls…

  • Monica – obviously do not eat Sushi – what is so hard about becoming a vegetarian?

  • LUCKY CATS?????????

    JKC | May 2, 2012 12:48 AM|

    Interestingly, I have a 19 year old CAT who came down with thyroid problems about 4 years ago, and her Vet,
    (a wonderful doctor-I wish I could find one as good for me)
    told me that thyroid problems in cats are also going through the roof.
    Sounds like the environment to me.

    No – it is their rotten food

  • Otnasnom

    Greenconsciousness: “what is so hard about becoming a vegetarian?”

    I’ll tell you: it is hard to hate the human animal to such an extent that our natural self is denied. Hard to hate nature that much. Hard to be so conceited as a race that we think we can moralise on the natural order and sweat like priests in a kindergarten when confronted with crispy fried bacon.

    But worst of all is the moralising, the self-denial, the refusal of visceral pleasure.

    So, in a nutshell, it’s hard to accept vegetarianism’s crypto-religious anti-nature, anti-human stance.

  • Anthro


    I find the greatest visceral pleasure in the preparation and consumption of a vegetarian diet. Why would anyone associate not eating the flesh of animals with hating nature?

    There’s no “moralizing”, just the way some of us choose to eat.

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  • Sam

    Nadine – Are you serious? I guess you have no problem writing off what has been a traditonal form of cuisine in Japan for centuries as silly. Next you’ll be calling the slow food movement, veganism, commenting on blog, etc as yuppie affectations….

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  • Otnasnom
    You are the one moralizing and you are ridiculous — hate nature?? What a joke — the joke of sadists who enjoy suffering and death — keep eating your pleasure — I like to think about the payback.


    It is too simple for them — they do not get that things have changed and this is not our grandparent’s food system. So let those trying so hard to be cool get good and cold thanks to their limited thinking. I hope they eat raw meat as well — it used to be served as a special treat at Italian weddings. Every tradition including stoning and 12 year old brides should be continued as tradition and ethnic tolerance!

    Some days I just lose tolerance and today is one of them– Vet prices into the hundreds for routine visits and I have to feed my cats this crap.

  • FarmerJane

    Yes, one of the industrial food magazines I get talks about the new process to recover protein from the water that is used to wash fish at sea. The article touted the environmental benefits if this protein can be sucked out of the wash water on all of the industrial-scale fish flotillas and brought back to mix into fish products.
    Americans are increasingly removed from their food sources, farming and fishing, so this blog is especially valuable in providing information.

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  • Samuraiartguy

    As a person of some Native American ancestry, I can’t weigh in on the vegetarian issues… as in the Lakota worldview every bit of everything we consume is wakan, it is sacred. Cows, carrots, corn, cod, the water, the air we breathe. And we should show appropriate gratitude and reverence for all our sustenance.

    However, I will STILL be avoiding supermarket sushi, and most prepared foods, for that matter. Because of the chili oil and spices used in the making spicy tuna rolls, a bastard product invented for gaijin, overwhelming the taste of the tuna, they can use patently substandard tuna products in their inexpert preparation. At least with a (hopefully) restaurant grade sushi chef, there’s a far better chance to enjoy sushi prepared with some care and expertise.

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