The truth about freezing salmon to kill parasites, please.

January 20, 2010 11:47 AM

I am seeking science-based answers (i.e., not dubious factoids passed along from one food blogger to the next) to the following questions: When making gravlax, 1) at what temperature and for how long must it be frozen in order to kill parasites, and 2) what is the risk of consuming gravlax that has never been frozen, both in terms of likelihood of getting parasites and what they'll do to you.

If it matters, this is wild Alaskan sockeye purchased the day after harvest at Pike Place Market in Seattle.

posted by HotToddy to Food & Drink (5 answers total)

Cooking for Engineers indicates that a 7 day period is safe: "Parasites, such as roundworms, can naturally reside in salmon regardless of if it was frozen or fresh. For safety, use salmon that has been commercially frozen or freeze the salmon yourself to at least -10°F (-23°C) for at least 7 days. Alternatively, you can freeze the salmon after you have cured the fish, but make sure you reach those minimum conditions."

This seems to be consistent with the FDA's information on parasites in fish, including salmon.
posted by webhund at 12:03 PM on January 20, 2010 [1 favorite]

Looks like this from the NY Times addresses (2). Seems like a pretty small risk, both of getting it and serious complications if you do. Other than the ick factor of:

''In the mildest and most frequent cases, the worm lodges in the throat and is coughed up"...
posted by cosmac at 12:20 PM on January 20, 2010 [1 favorite]

Wouldn't the curing process kill the parasites?
posted by BobbyDigital at 12:28 PM on January 20, 2010

The FDA recommends you follow any one of the following freezing methods:

at -4°F (-20°C) or below for 7 days (total time), or

at -31°F (-35°C) or below until solid and storing at -31°F (-35°C) or below for 15 hours, or

at -31°F (-35°C) or below until solid and storing at -4°F (-20°C) or below for 24 hours

posted by randomstriker at 1:59 PM on January 20, 2010 [1 favorite]

Response by poster: Thanks all!
posted by HotToddy at 8:18 AM on January 21, 2010