What is Sushi Grade??

[Maxed Out]

 When it comes to fish, I've heard the term "sushi grade" a lot and from what little I find on the subject it seems sushi grade is simply a phrase made up by fish mongers and there is no government entity or any official documentation that sets standards for sushi grade fish.

I'm by no means an expert on the subject, but according to what I've gathered about zero industry standards, anyone can say they're a sushi expert LOL

 Ted

[FatTuna]

All the tuna fish that we catch are sold to a local dealer who then ships them to Japan. From there, they are sold at auction.  Price is usually determined by supply and demand but also on fish quality. When the dealer looks at the fish, he takes a sliver of tail meat and a core sample to judge it. He is looking at how much fat the fish has. As well as the color of the meat. Sometimes the fish can have diseases or parasites that make them inedible. For example, white cloud. In my opinion, sushi grade fish is simply any fish that is edible raw. Some species of fish are edible but aren't suitable for sushi because they are prone to parasites. These are usually bottom dwellers.

[MarkT]

In my mind when someone says "sushi grade" they mean it was brought on the boat quickly, brain spiked, bled and put on ice to keep the meat in great shape.

[oc1]

Sushi grade cuts don't have any of that strong tasting dark stuff either.

A few months ago there was a local outbreak of hepatitis A from consuming raw tuna imported from Indonesia. It was mostly poke cubes but some sashimi too.  The Hawaii health department is telling people to inquire about the source before consuming raw tuna; insinuating that locally landed fish are OK.
-steve

[josephcsylvia]

I actually make sushi/sashimi quite often. Sushi grade is a term that some people think quality when they here it, and in certain circumstances it is. For instance a monger paying a fisherman for a really high grade tuna will say its sushi grade.
But in the culinary world it simply means that the fished has been frozen to a certain temp for x amount of time to kill parasites. Tuna is one of the only safe (relatively speaking) fish to eat raw without freezing. Salmon is the opposite and should never be consumed without freezing first.
Your home freezer isnt going to cut it either. Temps dont get low enough. Also if you are buying fish for sushi some things should be considered. If its in an open case with other non safe fish it is a no no. Also prep area should be different than non sushi fish prep are. No cross contamination. 

[Bryan Young]

This is copied from www.seafoodhealthfacts.org

"Parasites become a concern when consumers eat raw or lightly preserved fish such as sashimi, sushi, ceviche, and gravlax. When preparing these products, use commercially frozen fish. Alternatively, freeze the fish to an internal temperature of -4°F for at least 7 days to kill any parasites that may be present."

My home freezer is set for -8°F so I should be good.

I believe this differs if you use something that cooks the fish as well, such as lemon, lime, vinegar,...  I know when I used to work in a Sushi Bar, we used to take the salmon, soak it in a rice vinegar brine for 24 hours before consider serving raw.  This was salmon coming from the fish monger.

[Maxed Out]

 Parasites are one part of the equation, but just as concerning is "stromboid", which is believed to be a histamine that is formed under the skin on unproperly chilled fish. Some fish are more apt to have the stromboid bacteria and prevention is the best medicine.

For our local albacore there rule of thumb we go by that is also used by commercial boats. These are warm blooded fish and after a lengthy fight an albacore can have body temps over 90*, so cooling them fast is important for freshness. In order to prevent the stromboid bacteria from forming the whole fish must be chilled to the core to below 50* in 2 hours and below 40* in 3 hours(commercial fishers formula). We use commercial salted shaved ice and the tuna go into the ice right after bleeding.

 Stromboid can be cooked out of tuna, but not likely to happen at the low temps tuna is usually cooked to. Stromboid bacteria has symptoms similar to stomach flu and is quite often mistaken for some other ailment. If you google stromboid, you'll find a vast list of warm water species that are susceptible to forming stromboid bacteria. Anyone who eats raw fish should be educated about possible reprocussions to try and prevent them from happening.

 Ted

[philaroman]

my fishmonger's "sushi grade" comes out of a dedicated freezer...  each 1-2 lb. cut vac-sealed in heavy plastic

[Cor]

To me Sushi grade would mean, fresh fish, fat in good condition and not frozen, but that is personal and not a recognised standard.   Not frozen is not usually possible in a commercial environment.

I catch a fair number of Yellowtail and tag the majority, but ever so often and this happens more often in the early part of our season, I catch a fish that is strong and heavy for its length and is like a little barrel so fat.    Those have the misfortune of not getting a tag in the bum but a knife in the gills and I take them home for Sashimi.    Believe me you can taste the difference!

Just as a matter of interest, we prefer them to lay one day in the fridge before eating!

[jigmaster501]

Let me answer this from a regulatory perspective and being a seafood processing subject matter expert.

There is no legal/ regulatory basis for the term sushi grade.....

With that being said, the term sushi grade is used when looking at the fat content of the fish and how it appears once the fish is filleted or loined.

It is totally a quality issue.....

As for parasites, there are many species of fish that can be consumed without freezing as they are not considered a parasite risk. (that being parasites harmful to humans).....

Large tunas (bluefin, yellowfin, albacore, blackfin) are generally parasite free (human concern)....

They are not free from surface pathogens and no fish is for that matter unless chemically treated, steam surface pasteurized, irradiated, high pressure processed, or cooked....

Parasite control at home will need a CONTINUOUS -4F for 7 full days....Also, large piece over 6 inches in thickness generally will not work in this fashion without a scientific study. If you know someone with a blast chiller, you can freeze to -31F until solid and then holding at that temp for 15 hours CONTINUOUSLY, or you can chill to -31F until solid and hold at -4F for 24 hours.....

ACIDIC solutions do not destroy parasites in a short time frame and can take months to happen if it happens at all.

Changing temps during freezing will result in quality loss. Rapidly freezing, holding at that temp and rapidly defrosting (under controlled conditions) will result in the highest quality product.

A list of species and the corresponding potential hazards can be found at www.fda.gov (look up fish and fishery products hazards and controls guidance-4th edition 2011). Look at chapter 3 at potential species related hazards...The first column is parasites and if checked, your species is a parasite containing species. The 3rd columnn is histamines.....

Wild yellowtail contains parasites........


SCOMBROTOXIN (histamines) once formed CANNOT be cooked out of fish......Generally linked to scombroid species, there are many species other than scombroids that can create histamine not just under the skin but throughout the entire fish. Pelagics and bottom feeding fish can have histamines... This is why proper bleeding, evisceration, rinsing , vessel sanitation and rapid cooling are essential when dealing with histamine forming species. Once the enzyme histadine decarbolylase is activated, it can keep producing histamine under refrigerated conditions. The enzyme is formed by a several spoilage bacteria at elevated temperatures above 40F..... Improper evisceration can spread histamine forming bacteria all over the flesh creating a nightmare situation.... see www.afdo.org, look under resources and click on fish evisceration video. I did the video several years back...

The human body can breakdown low levels of histamine but other biogenic amines such as putrescine and cadaverine can potentiate low levels of histamine and cause a reaction to susceptable individuals.

In previous a previous discussion, I listed how you can reduce surface pathogens with a chlorine dip (not something you can do in a food establishment, but your only option at home unless you have access to the approved chemicals...)

Hope this helps..

Eugene

[Dominick]

Eugene thanks for weighing in on this subject.  It is always good to have an expert opinion.  Dominick

[Cor]

Let me answer this from a ....................
Wild yellowtail contains parasites........


Eugene

I've never really considered this and eat a fair bit of wild Yellowtail, raw!   Good mate of mine ate a lot more then me and never suffered any ill effects.

How common are the parasites,  how big is the risk to humans associated with this?
Is there some way to avoid it (other then not eating it) or to tell if the fish is infected?

Yellowtail occur in oceans worldwide, could the frequency of infection differ in different oceans of the world?

SCOMBROTOXIN refer to decayed fish is that related to Parasites in any way?

I do know that some people have a serious and dangerous allergy to something that is often found in Yellowtail?

Thanks

[jigmaster501]

Many of the parasites that occur can't been seen. Some can and can be candled and cut out. It is like playing Russian roulette. Symptoms of parasites often called Anisakiasis (from the genus of a parasite Anasakis spp.) often go untreated and are thought of as gas pains and other things but the parasites are actually burrowing through the lining of your intestines. The issue is commonly found while doctors are treating other gastrointestinal issues. The Japanese have the highest rates of Anisakiasis and it is generally found when searching for other illnesses. The Japanese eat the most raw fish on Earth....

The "allergy" in yellowtail likely comes from histamines....

Scombrotoxin (histamines) is a product of temperature abuse which initiates decay but you can have high levels of histamines in fish that looks and smells totally fine but was temperature abused.

[Maxed Out]

Wow Eugene, this is exactly why I started this thread. I was hoping for someone such as yourself to educate us on raw fish, and you just quadrupled the amount of info that can be found on google search  !! Thanks for taking the time to explain it in laymans terms. Most the info I posted came from memory of google searches, so I likely "misremembered" a few things.

[jigmaster501]

I have been doing this for many years.

I have been seen things that would make the average person scream....lol

Out of all the different arenas of food processing, seafood processing is by far the most complex and difficult to master.

There are many armchair experts who make tons of money giving bad advice to people in the food industry...

Most seafood has lost half of its shelf life and quality just by mishandling. Much of that takes place on the vessel.

Recreational fishing practices really destroy the quality of fish...Simple changes in handling which might mean a tiny fraction less fishing time can make a world of difference in the quality and safety of the fish being caught. Generally I might not catch as much fish and everyone else, but my fish goes home with the best quality.
If I can't bring the fish home in the best quality possible, I don't want to catch it.

I am trying to set up a seafood safety seminar for recreational fishermen here in NYC... Hopefully in the next month or two...