金槍魚分切全圖解：從整條到分塊的專業切割技術

2026-03-18 · 8 min read · 稻荷環球食品

Professional Tuna Butchering Guide: From Whole Fish to Perfect Portions

Tuna butchering is a specialized skill that transforms a whole fish into market-ready portions with maximum yield and minimum waste. Whether you operate a sushi restaurant in Macau or manage a seafood distribution business, mastering these professional cutting techniques will elevate your product quality and profitability. This guide covers essential tools, tuna anatomy, step-by-step cutting procedures, and preservation methods used by professional chefs and fishmongers worldwide.

Essential Tools for Professional Tuna Butchering

Quality tools are fundamental to achieving clean cuts and maintaining fish freshness. Professional tuna butchers rely on specific equipment:

• Long-bladed yanagiba knife (300-330mm): The primary slicing knife for loin removal and portioning
• Deba bocho (150-180mm): Heavy knife for head removal and bone separation
• Flexible filleting knife: For trimming and detailed work around bones
• HonING steel: Essential for maintaining razor-sharp edges during extended work
• Cutting board (marine plywood): Non-slip surface that protects knife edges
• Fish scaling tool: For removing scales if working with whole tuna
• Clean cloths and ice: For temperature control and cleanliness

Always keep your knives razor-sharp. Dull blades crush fish fibers, compromising both appearance and shelf life. Sharpen between each fish or every 20-30 minutes of continuous work.

Understanding Tuna Anatomy

Before cutting, familiarize yourself with tuna anatomy to maximize yield and identify premium cuts:

• Head: Contains the cheeks (highest quality for sashimi) and collar (rich in omega-3)
• Collar: The shoulder area near the gills; prized for its fat content
• Main body (loins): The two symmetrical red muscles along the spine; the primary source of loin cuts
• Belly (harakami): The ventral section; contains the richest fat marbling
• Tail section: Leaner meat, excellent for grilling or canning
• Blood line: The dark red area along the spine; has strong flavor and should be removed for premium products

Bluefin tuna (真鮪) is the most prized variety, followed by yellowfin (黄鳍金枪鱼) and bigeye (大眼金枪鱼). Each has different fat distribution patterns affecting cutting approach.

Step-by-Step Tuna Butchering Process

Step 1: Initial Assessment and Cleaning

Inspect the tuna for freshness: bright red gills, clear eyes, firm flesh, and sea-fresh odor. If working with a whole tuna, rinse thoroughly with cold seawater or fresh water. Pat completely dry with clean cloths—moisture dilutes flavor and promotes bacterial growth.

Step 2: Head Removal (Ikachime)

Place the tuna belly-down on the cutting board. Make a clean cut just behind the gill plate (angling slightly backward) using a deba bocho. For larger tuna, you may need to saw through the thick collar section. Remove the head completely, reserving the collar for separate processing.

Step 3: Belly Opening and Gut Removal

Turn the fish belly-up. Make a shallow incision from the anal opening toward the head, carefully avoiding the belly wall. Open the belly cavity and remove all internal organs. Scrape the cavity clean, removing all blood clots and membranes. The belly flap (harakami) should remain attached.

Step 4: Loin Removal (Hagashi)

This is the critical step for yield optimization. Turn the fish belly-down. Starting from the tail end, insert your yanagiba knife just beside the spine. Guide the blade along the rib bones toward the head, maintaining consistent pressure. Repeat on the opposite side to separate both loins from the frame.

Key technique: Keep the knife parallel to the bones for maximum loin thickness. A slight inward angle toward the bones ensures complete meat removal.

Step 5: Skin Removal

Place each loin skin-side down. Hold the tail end secure and slice between flesh and skin using a pushing motion. Work from tail toward the head in one continuous stroke. For premium sashimi, leave a thin layer of fat on the skin side (this enhances flavor when seared).

Step 6: Blood Line Removal

Locate the dark red blood line running along the center of each loin. Using your filleting knife, make a shallow cut to excise this section completely. This step is essential for premium-grade tuna—failure to remove the blood line results in strong, gamey flavors and rapid discoloration.

Step 7: Portioning

Cut loins into appropriate portions based on your needs:

• Sashimi portions (saku): Rectangular blocks, typically 2-3cm thick, 6-8cm wide
• Steak cuts (hiraki): Cross-section cuts, 2-4cm thick
• Keel cuts (sujiki): Angular cuts from the loin edge, popular in Japanese markets

Quality Preservation Techniques

Proper handling after cutting determines product value and customer satisfaction:

• Immediate refrigeration: Store portions at 0-2°C (32-36°F) immediately after cutting
• Proper wrapping: Use vacuum packaging or tightly wrapped plastic film to prevent oxidation
• Ice storage: Place portions on ice, not beneath it—ice meltwater damages flesh texture
• First-in-first-out: Label all products with cutting dates; use within 2-3 days for peak quality
• Temperature monitoring: Regularly check storage temperatures; never exceed 4°C (39°F)

For long-term storage, flash-freezing at -40°C (-40°F) preserves quality for up to several months. Thaw slowly in refrigeration, never at room temperature.

Common Mistakes to Avoid

Professional butchers should avoid these frequent errors:

• Using dull knives that crush rather than cut cleanly
• Leaving the blood line in premium cuts
• Storing tuna on direct ice (use drainage systems)
• Rushing the process—patience yields better results
• Neglecting to clean tools between fish (cross-contamination risk)

Conclusion

Mastering tuna butchering requires practice, quality tools, and attention to detail. By following these professional techniques, you can maximize yield while delivering premium-quality products that meet the expectations of discerning customers. Remember: the difference between good and exceptional tuna lies in the precision of the cut and the care of the handling.

For Macau's seafood professionals, investing in proper training and equipment pays dividends through reduced waste, higher product value, and customer satisfaction. Whether you're preparing for high-end sushi service or wholesale distribution, these skills form the foundation of a successful tuna operation.

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