What is the grading classification of tuna?
There are four grades of tuna that are commonly used in the market.
- Grade 1 Tuna - The highest grade of tuna. It is called sushi grade or sashimi-grade as sashimi requires the freshest and the highest quality of tuna. In order to be graded #1, a tuna must exhibit all #1 quality of all five indicators.
- Freshness
The collar where the head has been removed should be clean with no discoloration.
The skin should be clean as well without any puncture, scratch, or damages.
Specific color differs by species but in general, a tuna’s original exterior color should be a reflective, metallic black. The scales should be intact as well.
The belly should be clean and intact. A damaged or stained belly indicates spoiled meat. The color should be pink.
The tuna should be firm to the touch.
- Size and Shape
Should be at least 60 pounds or larger since heavier fish have a more desirable loin size and fat content.
The shape should be fat and round with a thick belly.
- Meat Color
The tuna should be bright red, shiny, and translucent. The core and tail sample should have this color.
The bloodline from the samples should be a darker red than the meat. It should not be black or brown.
There should not be any discoloration or brown under the skin where the fat is located.
- Texture
Tuna should have a fine and smooth texture, not coarse or grainy.
The core sample should be clear and the fat should be felt when rubbing it between one's thumb and index finger.
The core sample should be sticky to the touch.
- Fat
Fish with high-fat content is generally regarded as more valuable and are priced higher.
A thick belly is usually an indicator of high-fat content.
Fat content should be visible at the nape where the head has been removed.
The presence of fat in the tail cut, just below the skin is essential in grading.
The fat is visible in the meat like the “marbling” seen in beef.
- Grade 2+ Tuna - The next grade of tuna following #1 grade. This grade is relatively new in US markets and has only been used since the 1980s. The disparity between #1 and #2 was great so this median grade was created.
- Freshness
Grade #2+ tuna might be close to Grade #1 tuna in skin color.
The nape and the belly might be slightly flatter and not as bright.
The outside should be clean, but with some small scarring and wounds acceptable. The scars should not be severe to affect the fish’s quality.
A few imperfections on the scales and skin.
Fins should not be broken.
- Size and shape
The size and shape should resemble #1.
Grade #2+ may be smaller than 60 pounds.
The shape may be less perfect than #1, but should not be inferior. This fish is usually longer and thinner as opposed to fatter and stockier as in #1 grade.
- Meat Color
The tail cut is red but might be slightly discolored near the skin.
Color is the most important factor when determining a Grade #2+ fish. The core sample should be red with less clarity than Grade #1.
The loin cut is slightly less bright than Grade #1.
Less consistency in color throughout the loin.
Evidence of fading color from the top of the loin to the bottom near the skin may be seen.
- Texture
Has less fat so the texture feels less sticky and leaner.
It should still feel wet and smooth as in Grade #1.
It should still have a good and solid feel to the touch.
- Grade 2 Tuna – This is the tuna of choice of many restaurants that don’t want to pay Grade #1 money for tuna dishes that will be cooked. Although this grade is not really considered sushi-grade, some low-end restaurants may use it raw.
- Grade 3 Tuna – This is a cooking grade, and the color has already turned brown or greenish.
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