Once a bluefin tuna is caught, it arrives at Toyosu fish market within a day or two. However, that fish is not used as a sushi topping that day. No matter how good the tuna is, it starts very stiff and is not in a state where it should be eaten. The meat is hard and the white muscle lines are left in your mouth. The odor and acidic taste of the red meat is strong and the unique sweetness of the fish is nowhere to be found. After it has rested the muscles soften, bringing out the fat.
Then, when the sushi chef gets the tuna, he first separates the red, lean meat and the fatty toro portion, rewraps them separately, seals them in plastic, and puts them on ice. Next is waiting for the “young” meat, not yet suitable for eating, to mature. The number of days the fish will be rested depends on the size of the fish and the temperature. The smaller the cut and the warmer the temperature, the shorter the rest time. Generally the time is from 3-14 days.
The tuna wholesaler may also decide on the aging period independently. There is no right answer for this aging period, and it is decided based on the experience of the sushi chef.
This “young” fish not ready for consumption is a fresh, deep color but as it matures the color darkens, the fat is brought out and becomes a fleshy color. Proper care must be taken because if it’s rested for too long, the color changes too quickly.
As an aside, right after the tuna cutting show, it has not yet aged enough to be delicious. The color is light, and the production of umami ingredients such as inosinic acid is not sufficient. This is a show for advertising purposes.
Related contents: TYPES OF TUNA
We hope this information will be helpful.
Revision date: March 11, 2025
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