Halibut or Flounder hirame : Halibut is very delicate in taste and is often one of the first dishes to be consumed. What are parasites? What is sushi-grade fish? Fresh or frozen? Follow these tips and you should be on your way to creating a delicious homemade sushi! Make a reservation. View All Events. Love being the first to hear about the latest events, offers and special promotions? Sign-up to our newsletter now to keep up to date. True sushi tuna is meant o be used raw, in very thin slices.
Tuna is usually more expensive than salmon, and both are traditional sushi toppings. The way tuna is used in sushi is meant to showcase its flavors. On a nigiri — just rice and a dab of wasabi, tuna really shines and you can taste all of it. The main thing is that sashimi is raw meat, cut a little thicker than sushi tuna. This means you need to taste it in all its glory, so you need to use some damn good tuna. So sashimi is meant to be enjoyed as more of a delicacy than an actual meal you fill up on.
You may be thinking that raw meat is just raw meat, how is there any difference between them? It's a paradox: The FDA will not deem a fish free from parasite hazards, and thus safe to eat raw without freezing, unless that fish is eaten raw, without being frozen, frequently enough to present sufficient evidence of its safety. To Luke Davin, the general manager of Osakana, this standard means that "deviating from [the FDA's] 'freeze it all' approach puts the burden of testing and proof on the processor.
The easiest solution, then, is simply to freeze everything. Despite the FDA's blanket recommendations for the elimination of parasites, which is the main goal of its freezing guidelines, very few infections from eating raw fish have been documented in American medical literature.
In the US, eating raw fish that hasn't been frozen is rare enough that the agency's "Bad Bug Book" uses Japan as a reference point, since the practice is far more prevalent there.
But even in Japan, where freezing of fish meant for sashimi is not required, reported infection rates are vanishingly small compared to the total population. Because some infections are asymptomatic, and many are thought to go unreported, the risk of infection may be greater than statistics suggest. On a less scientific level, worms—particularly parasitic worms—inhabit dark recesses of our collective imagination.
The idea that eating a piece of seemingly pristine, delicious fish carries a risk of infestation by alien-like organisms is enough to give anyone—including health authorities equipped with all the relevant, fear-assuaging data—the heebie jeebies. Both Haraguchi and Herron point out that, in certain cultures, fish has long been served raw despite never having been frozen at all, and neither was bothered by the idea of eating fish under those circumstances though they stress that the fish they sell for raw consumption has been frozen according to FDA guidelines.
Of parasites, Haraguchi says, "It's natural. Parasites are as natural as seeing a ladybug in farmers market vegetables. I'm fine, you're fine. And everybody was doing that before these regulations came out, and everyone was okay. But there are caveats: Freshwater fish and some anadromous fish—fish, like salmon, that divide their life cycles between fresh and salt water—are susceptible to broad fish tapeworms, which are widely considered more harmful than other parasitic worms.
Few experts recommend eating fish in the cod family—particularly Atlantic cod, but also Pacific cod, haddock, and pollack—since they're highly susceptible to infection by a range of parasites. According to Haraguchi, there's another reason fish in the cod family are not eaten raw: "There's so much moisture [in the flesh], it doesn't taste good. The parasites that infect most marine fish are nematodes, or roundworms, from the genus Anisakis. It's preferable to avoid eating them, of course, but conventional wisdom says that the stray live anisakid in your gut will, at worst, provoke some discomfort—nausea and possible stomach pain, similar in kind to a bout of food poisoning.
Judy Sakanari, a parasitologist in the Department of Pharmaceutical Chemistry at the University of California, San Francisco, believes that this view downplays the risks of ingesting anisakids. Sakanari stresses that understanding the life cycle of the parasite is necessary to a full appreciation of the risks involved. All parasites seek to reach their end-host organisms. For tapeworms, these are bears and other fish-eating mammals; for anisakids, they're marine mammals, such as whales, seals, and dolphins.
If all goes as the parasite gods intend, fish carrying infectious worm larvae will be consumed by an end-host organism. But if those fish are snatched up in a trawler or caught on a line, the ideal parasitic life cycle is interrupted. As soon as the fish's body temperature begins to rise to that of the end-host mammal, the parasite larvae in its gut will attempt to find a way out, leading them to burrow into the fish's flesh.
This is one reason why it's always best to keep ungutted fish cold: Any parasite larvae in the fish gut will remain immobile as long as the temperature is sufficiently low. That impulse to find a more hospitable environment, Sakanari says, is what makes anisakids particularly worrisome for humans. The human body is sufficiently different from that of whales and elephant seals—typical anisakid end hosts—that it forces the worms to wander around inside of it.
As they do so, they probe along the intestinal wall, trying to penetrate it and sometimes getting stuck in the process, which can necessitate resection. Interestingly, because humans are a natural end host for tapeworms, Sakanari says that tapeworm infection, as disgusting as it might sound, would be preferable to larval anisakid infection. The pathologies associated with the adult fish tapeworm infection are by and large less severe, and can be treated with a simple anthelmintic.
Sakanari notes that preparations like ceviche, in which fish are submerged in an acidic bath, do nothing to kill off anisakids, since they thrive in highly acidic environments.
Candling—in which a strong light is shined through thin fish fillets placed on a glass, in order to spot parasites to be removed—is also not foolproof: Sakanari describes an experiment in which she and her colleagues examined a piece of rockfish using this method and determined that it was free of parasites. After cooking, they then flaked the fish fillet and examined it, and found that they had in fact missed several worms.
Even experts can fail to completely deworm a fillet. The upshot of all this: The only real way to be sure that you've eliminated any parasites in the flesh is by using temperature. That's the bottom line," Sakanari says. Is it worth the risk to eat raw fish that hasn't been properly frozen? Haraguchi and Herron agree that parasites in raw fish are less of a concern than bacterial contamination.
Once the rice is acidified, time is not used as a control and therefore it can be stored at room temperature where the quality is best and it is also easiest with which to work. When you eat sushi from a quality establishment, you may expect that the FDA requirements for parasitic destruction have been followed, however you are at the mercy of the preparer to make sure that subsequent to being frozen and thawed, your food has been handled properly. Good sushi is, in my opinion, well worth the minimal risk.
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