in August, New York City will require that fish served raw in restaurants be frozen before serving, according to The New York Times. For purist diners of sushi and sashimi who may take offense at the idea of their fresh catch coming from a freezer, the new food safety law is meant to ensure that bacteria and parasites don’t come with it. And, as it turns out, a number of restaurants are already freezing their fish as a safety precaution, with most customers being unaware. The new rules require restaurants to keep their fish frozen for anywhere from 15 hours to a week, depending on the temperature setting of the freezer. A number of seafood products are exempt from the rules, including shellfish and farm-raised fish. One restaurant, Sushi Zen, has been deep-freezing its fish to -83 degrees F for years to eliminate the threat of parasites and other harmful pathogens. Additionally, the majority of the fish sold in the U.S. is flash-frozen somewhere along the supply chain to maintain freshness. Raw fish served as sushi and sashimi has caused a few foodborne illness outbreaks in the U.S. in recent years. Most recently, sushi was believed to have caused at least 50 illnesses in a nine-state Salmonella outbreak. In 2012, raw tuna contaminated with Salmonella caused an outbreak that sickened more than 300 people in 26 states. The new law will go into effect in August, so the clock is ticking for any sushi aficionados who wants to dine a little more dangerously. (To sign up for a free subscription to Food Safety News, click here.)

  • Mike_Mychajlonka_PhD

    Most folks seem to agree that freezing is a good kill step for parasites in fish. However, this article cites outbreaks of Salmonella infections following ingestion of raw fish as examples of the dangers of eating raw fish. It is generally known that freezing by itself is not an effective kill step for bacteria. A paper [Aldsworth, T.G. et al. (1998) Applied and Environmental Microbiology Vol. 64, No. 4, pp. 1323-1327] shows that freezing a pure culture of Salmonella allows for approximately a 0.4% survivorship, nothing to write home about. Furthermore, they show that in the presence of a mixed culture (something one might expect to find in raw fish) the survivorship of Salmonella increases to 4%. Freezing may well be a good answer to disabling parasites embedded within fish and New York City may be right about insisting upon its use for that purpose. However, it seems misleading to allow the inference that freezing may protect consumers from Salmonella.

  • Ron C

    Freezing foods renders bacteria inactive but doesn’t actually kill anything. That means if your food went into the freezer contaminated, once thawed it will still harbor the same harmful bacteria. Cooking it to the recommended temperature is the only way to ensure that your food is safe. How does this help? Not sure I get what happens at -83?

    • FoodLover

      I agree. The Salmonella spp. link doesn’t make sense, but the freezing for parasite destruction does. I am actual shocked that NYC didn’t require this previously. In the small county where I live, fish intended for raw consumption has been required to be frozen for about 15 years. One sushi place didn’t follow the rules and there was an outbreak of D. latum– a really, really long tapeworm.

  • Heatheryp

    I don’t think you can kill Salmonella from freezing so the food borne illnesses from bacterial pathogens such as Salmonella would still occur.