Tuna Part Classification part 2 – Different parts of the Bluefin Tuna - Otoro, Chutoro, Chutoro, Akami and special parts
Division of the Tuna parts by fat content – Why tuna parts have different oil contents/ Overview of Akami, Chutoro, Otoro, Setoro
Animals including humans and tuna store energy in the adipose tissue. Especially, the subcutaneous adipose tissue that are right beneath the skin are the first locations where humans and even tuna start to build up their fat and oil.
Thus, the tuna meat closer to the skin have higher oil contents as the hypodermis have much more subcutaneous adipose tissue.
The flesh and meat becomes much leaner and have less oil content as it gets further from the dermis(skin).
Also, there are much more subcutaneous adipose tissues located near the stomach and the belly, thus distinctive flavors develop per regions.
The back region of the tuna has the akamiあかみ(赤身), the red meat and the setoro(背トロ), the lean and oily meat(some calls this the chutoro as well but the Japanese term ‘se’ 背 means back so the oily back region is a much specified term)
The belly region has the Otoro(大トロ), the highest oily part of the tuna and the chutoro(jutoro, judoro), 中トロ the oily part with great oil and lean meat balance.
Akami – redmeat of tuna 赤身(あかみ) – Back of tuna
The Japanese term akami literally translates as red meat and most of the back loin of the bluefin tuna is red meat the akami. The Akami part consists most of the bluefin tuna and it is very lean with the least oil contents.
The distinctive red color comes from the myoglobin that is a pigment in the muscle that stores oxygen for metabolism. The red color itself is technically oxidized iron like red blood.
Setoro / Chutoro – oily meat on the back of the tuna – back of tuna
Restaurants may have different names for the oily meat on the back of the tuna near the skin. Some would refer it to Setoro or Sedoro in Japanese 背トロ or some would claim this is also the chutoro(中トロ).
Setoro means the toro of the back(se means back) while the cutoro means medium melting thus the medium oily contented meat.
For those that would like to enjoy the flavor of tuna while avoid too much oil and fat actually prefer the setoro region.
Chutoro – medium-fatty part of the tuna – belly of tuna
The term toro(トロ) derived from the Japanese term “torokeru とろける” that means ‘melt away’ or ‘dazzling feeling’.
The Japanese would name the belly fatty regions of the bluefin tuna the ‘toro’ (トロ) as the bluefin tuna’s belly region has high fatty region that not just melts in the mouth but also has a dazzling test.
The name Chu or Ju 中 means medium in Japanese so the chutoro or the judoro means the medium-fatty or semi-fatty part of the tuna.
The chutoro region isn’t the region towards the tail but rather the dorsal region of the tuna belly along the dorsal-ventral axis(belly to back) Chutoro has the lean meat flavor and the fatty oil content that melts in the mouth.
Otoro – most oily meat on the back of the tuna – back of tuna
Otoro(Odoro) 大トロ, Oh means ‘large’ or ‘big’ and the Japanese name means the most oily meat in the tuna. The Otoro when consumed raw as sashimi or sushi would melt right away in the mouth due to the high fatty oily contents with a low melting point.
People may not prefer the strong tuna flavor and high fat(oil) content of the tuna. Still the Otoro is called the king of the tuna parts.
Kamatoro – back cheek part between the fin and the gills – neck of tuna
The kamatoro かまトロ means the toro part that looks like a sickle. The kamatoro refers to the part back of the cheeks and between the gills and the fins thus the neck of bluefin tuna.
The kamatoro cut is the most expensive cut as it has the highest fatty part composition throughout the cut. If the Otoro is the king, the Kamatoro is the emperor. The kama part of most fish are typically the most expensive due to the rich flavor.
Shimofuri – Filet mignon of the bluefin tuna otoro
霜降, しもふり Shimofuri literally means snow and it is a description of the upfront of the harakami region the front belly. Like the filet migong is the tip of the tenderloin, the shimofuri is the tip of the belly of the bluefin tuna(Of course tenderloin is lean and beef)
The Shimofuri is the otoro region with the riches oil content and has a marbling of fat like wagyu that gave the name ‘snow’ shimofuri.
Sunazuri – belly button of the bluefin tuna
Sunazuri すなずり means sand rubbing and refers to the chicken gizzard sometimes. This part looks like some dots in the belly region so it is called the belly button of the bluefin tuna.
However the Sunazuri is rather more of the meat right next to the hotracic diaphragm of the bluefin tuna and it isn’t the belly button part.
It is usually found a lot in the number 3 toro cut and may be absent in the kamtoro and the #1 toro. (Bluefin tuna belly is cut to kamatoro, #1 toro, #2 toro etc from the gills to the tail. Kamatoro is the most expensive followed by #1,#2…..)
In South Korea there are some misconceptions that this is the most expensive part but it is good marketing.
Hoho-Niku: cheeks of the tuna
ほほ肉is the cheeks of the bluefin tuna. Cheeks of fish have a firm texture and is one of the delicacies of all fish.
Nōten: forehead of the tuna
脳天 means the forehead of the bluefin tuna. It is one of the secrets of choosing quality bluefin tuna, however the contents of the forehead of the tuna is important to determine the quality of the bluefin tuna.
Bluefin tuna with a large forehead with a high chance has high fat and oil contents in the body. It has a taste similar between the chutoro and the otoro.
Negitoro – diced green onions with the toro
ネギトロ negitoro means green onion with the toro. This isn’t a part of the tuna but rather a dish served with the several cuts of the bluefin tuna served with diced green onions.
Nakaochi – rib meat of the bluefin tuna
中落ち Nakaochi means scraped from the bones, middle of the bone and it is the meat scraped form the backbones and the ribs of the bluefin tuna.
