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tuna-sashimi

How is tuna graded?

11/04/2016

Like any premium product, fresh tuna is priced based on how it is graded. This is especially true for tuna headed to the sushi kitchens of the world, where appearance and taste are scrutinized with every bite.

Each tuna can earn one of four grades: #1 (highest), #2+, #2, and #3. While this grading is highly subjective, over time a system has evolved to help guide fair pricing. Like the 3 C’s in diamond, each fish is graded based on five indicators:

Initial appearance

Size and shape

Color

Texture

Fat content

Initial appearance (freshness) is where the grading process starts. Most tuna is traded headless, and one of the most apparent signs of freshness is the collar, where the head has been removed. Then the fish’s skin, scales, and fins are visually inspected. Once the outside is evaluated, then the inspector looks inside, at the belly wall, to grade based on what is visible from the cut made to gut the fish

Size and shape – The size of a fish and its marketable yield are directly proportional. Larger fish produce larger loins and fatty portions, which increases their value.

Color – Tuna’s meat is generally red but the specific level of redness determines the grade. The tail color (from where the tail is cut off) is a good indicator of the condition of the fish since that area tends to change color first. The color of the core sample and the bloodline are also good indicators of health and general quality.

Texture is best determined by physically feeling the core sample and the tail cut. The stickiness or pastiness of the core sample and the smoothness of the cut of meat are good indicators to determine tuna’s grade

Fat – A tuna’s grade depends also on its fat content. The best places to determine fat content are the core sample, belly wall, tail cut and the nape (collar).

Tuna should never be soggy, watery or tasteless as these are indicators of poor quality or thawing.

Citations:

http://www.luxegourmets.com/shimazaki-column/tuna-grading-system
http://www.soest.hawaii.edu/PFRP/soest_jimar_rpts/bartram_garrod_kaneko96.pdf
http://www.chubbyfish.com/how-we-grade-tuna/

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