I have been getting my tuna for sashimi frozen, but a local sushi chef tells me it is much better fresh.
A local seafood outlet, which supplies many local restaurants and has an excellent reputation, has fresh "sushi grade" yellowfin tuna, but tells me it should be frozen for at least an hour before it can be served raw. The manager says he has a number of "sushi grade" species, but says they all should be frozen first. And he says the fresh cobia should not be eaten raw at all.
I want to eat it fresh, but am concerned. Is it required to freeze fish before serving it as sashimi? And is Cobia not suitable as sashimi at all?
Tuna doesn't have to be frozen at all. All raw fish can make you sick. Keep it cold, serve it with ginger, shiso, wasabi(all digestive aids and cleaners). The number one tool a sushi chef has is the ability to tell for himself what is good tuna and what is bad.
Parasites are far less common in Tuna because they are strictly deep, cold saltwater fish. Salmon live in rivers part of the time, and are rife with worms and whatnots.
The main concern is getting it fresh. A tuna is a big fish, and there have to be a lot of folks wanting the best tuna in Tallahassee to get good quality tuna fresh. I was lucky to work at a bar where the customers would call each other and come in twice a day if they liked the fish. We killed $1100 of Bluefin in a single day.
Scombroid or Histamine poisoning is usually aasociated with tuna that has been time/temp abused, and possibly Ciguatera in regards to Cobia. Freezing will not render either of these toxins inactive. The other concerns are biological parasites. In this case, freezing will kill the majority of these nasty little buggers.
Freezing is not necessarily a bad thing if done correctly, but home freezers won't freeze fast or deep enough to maintain top quality. Most if not all of the top sashimi grade tuna that passes through Tsukiji is frozen at sea anyway, and nobody has issues with that. If you can find it, fresh Kindai tuna would probably be pretty safe.
In the states I think pretty much anything labeled "sushi grade" has been flash frozen. It's a government regulation thing. The USG says that flash frozen fish that has been maintained a specific low temperature for a certain amount of time is safe for raw consumption, and won't put it's stamp of approval on anything else. And properly flash frozen food is just as good as fresh. Tiny crystals.
Originally Posted by Keith Neal
as said before obey the time temp rules and you should be good.
And you might as well drink some white wine while you are at it. Alcohol is one of the best preventatives for food poisoning. About 5 years ago or so when a some cruise ships had massive outbreaks of food-borne illnesses, those who drank high alcohol drinks (i.e., not beer) with high acidity (think: white wine) were not affected. I'm sure saki works too.
Originally Posted by johndoughy