Tutorial 12.1 The Ultimate Guide to Tuna Selection and Preparation for Sush

I. Selecting Sushi-Grade Tuna

A. Color Guidelines

• Fresh tuna: Deep red shade

• Aging tuna: Darkens to brownish tint (past prime, no longer sushi-grade)

B. Avoiding Processed Tuna

• Some tuna treated with carbon monoxide (CO) gas to retain color

• CO-treated tuna: Bright pinkish color

• Natural tuna: Blood red color

• Issues with CO-treated tuna:

  • Lacks flavor

  • Difficult to determine freshness

  • Banned in some countries (not in the US)

C. Tuna Cuts and Their Characteristics

1. Otoro:

   • Located in belly quarter

   • Highest fat concentration

   • Most desirable and expensive

2. Chutoro:

   • Medium fatty tuna

   • Located above the skin in larger fish

   • Quality depends on fish size

3. Akami:

   • Leanest part, closest to spine

   • Most affordable cut

D. Tuna Species for Sushi

1. Bluefin: Highest quality and price, rarely found in retail

2. Bigeye: More widely available

3. Yellowfin: Common in local stores

E. Tuna Grading System

• Based on color, clarity, texture, and fat content

• Scale: 2 (worst) to 1+ (best)

• Generally, only #1 grade used for sushi

II. Preparing Tuna for Sushi

A. Purchasing Tips

• Buy a section of loin, not the whole quarter

• Avoid tail end (too much sinew)

• Ask fishmonger to remove bloodline and skin

B. Initial Preparation

1. Dry the loin thoroughly with paper towels

2. Cut off the Akami half (about 1/3 from the top)

C. Cutting Technique

1. Cut loin lengthwise into 1-inch thick blocks (Saku cut)

2. Cut parallel to the loin

3. Reserve end piece with stronger connective tissue for spicy tuna or hand rolls

D. Trimming and Sorting

1. Remove any remaining bloodlines

2. Trim visible sinew, especially near the skin

3. Keep trimmings for later use

4. Cut Akami half into smaller pieces (leanest and most tender part)

E. Storing Cut Tuna

1. Wrap pieces in saran wrap to prevent drying

2. For longer storage, wrap in deli paper and refrigerate

3. Use within 3-4 days

4. Change paper every other day to keep dry

5. Optional: Sprinkle with salt to reduce bacteria

III. Utilizing Tuna Trimmings

A. For Sushi Rolls

• Cut trimmings into smaller pieces

B. For Scraped Tuna (Spoon Meat)

1. Fillet pieces with strong sinew into thin slices

2. Tenderize with back of knife

3. Scrape meat off sinew with a spoon

4. Use for rolls or tuna tartare

C. Freezing Excess Tuna

1. Spread thinly on parchment paper

2. Wrap in saran wrap

3. Freeze immediately to preserve color and quality

4. Defrost for a couple hours before use

5. Use within one week

Remember, mastering tuna selection and preparation is crucial for creating high-quality sushi. With practice, you'll develop an eye for selecting the best cuts and efficiently preparing them for various sushi applications.