Preparation & Cutting Technique

Boning & Filleting

Boning and filleting are the two most time-intensive preparation techniques in the professional kitchen. Master tunnel boning for ballotines, the butterfly cut for roulades, and the four-fillet method for flatfish. Including HACCP protocols for Anisakis, knife sanitisation, and cross-contamination prevention.

4 fillets per flatfish (sole, halibut, brill)

55-62% boning yield whole chicken

82 °C knife sanitisation NVWA guideline

0-2 °C max. storage temp. fish during filleting (EU 853/2004)

Requirements

Boning knife 15-20 cm (stiff for beef/lamb, flexible for poultry) Filleting knife 20-25 cm (thin and flexible) Probe thermometer Tweezers for pin bones Ice water to keep fish at temperature

In brief

[DEFINITION] Boning & Filleting

Boning is the removal of bones from meat or poultry so the flesh remains intact or available as a flat sheet for roulades, ballotines, or portioning. Filleting is the separation of fish flesh from the bone structure: two fillets for round fish (salmon, sea bass), four fillets for flatfish (sole, halibut). Both techniques determine the final yield and food safety of the end product.

Tunnel boning: the bone is removed through a small opening without cutting the meat open. Used for ballotines and galantines of poultry, where the meat remains intact like a "sock". (CIA Professional Chef, 9th ed., Wiley, 2011)
Seam boning: boning along the natural muscle boundaries. Yields separate muscle groups suitable for direct portioning. Standard method for lamb shoulder and leg.
Butterfly cut: the meat is opened out like a "butterfly". Used for lamb shoulder or lamb loin when a thin, even sheet of meat is desired for stuffing and rolling.
Round fish filleting: the spine serves as a guide. First cut along the spine on the dorsal side, second cut along the belly side. Pin bones are felt with the fingertips and removed with tweezers in the direction of the head. (Le Cordon Bleu, Fish & Shellfish Masterclass, 2005)
Flatfish filleting via the four-fillet method (Escoffier, 1903): the central bone structure serves as a reference. An incision along the centre line, then four fillets are lifted free. Sole yield: 45-50%; halibut: 55-60% due to thicker fillets.

Three methods of boning

Tunnel boning (poultry)

Bone removed through a small opening, meat remains intact like a "sock". Essential for ballotines and galantines. Time-intensive but yields the finest presentation without visible cut surfaces.

Examples: Applications: ballotine de poulet, galantine, chicken stuffed with farce

Butterfly cut (meat)

Meat opened out like a butterfly: uniform thickness for stuffing and rolling. Butterfly-cut lamb shoulder yields one large flat piece of meat approximately 1.5 cm thick for roulade or grill.

Examples: Applications: stuffed lamb shoulder, roulade, veal breast

Four-fillet method (flatfish)

Four fillets per fish from the central bone structure: two upper, two lower. Classic method for sole, halibut, and brill. Sole yield 45-50%; halibut 55-60%.

Examples: Applications: sole meuniere, halibut steak, brill with Hollandaise

Source: Escoffier, Le Guide Culinaire (1903); CIA Professional Chef (Wiley, 2011); Le Cordon Bleu, Fish & Shellfish Masterclass (2005)

Boning and filleting yield: professional benchmarks

Whole chicken

55-62% boning yield. 38-45% of weight consists of bones, skin, and fat. Neck and wing tips serve as raw material for chicken stock.

Method: tunnel boning or seam boning

Lamb shoulder

70-75% yield after full boning. Remainder: shoulder joint, wing bone, shoulder blade. Bones suitable for lamb stock.

Method: butterfly cut or seam boning

Salmon (round fish)

57-60% fillet yield. Head, spine, and tail: 40-43%. Bones and head suitable for fish fumet.

Method: spine as guide, pin bones with tweezers

Sole (flatfish)

45-50% fillet yield. Four thin fillets from a relatively heavy bone structure. Bones and head for classic fish fumet.

Method: four-fillet method (Escoffier, 1903)

Halibut (flatfish)

55-60% fillet yield. Larger than sole, thicker fillets. Head and bones for premium fish stock.

Method: four-fillet method

Monkfish (tail)

55-62% yield. Central spine removed yields two clean loins. No small bones: the most comfortable fish portion for guests.

Method: central spine removal

Yield differences of 5-10% have a direct impact of 15-30% on the cost per portion. Always measure your actual yield with your specific supplier.

Step-by-step method

1

Check fish temperature

Inspect the fish before filleting: eyes clear and convex, gills red, scales shiny and firmly attached, flesh springs back when pressed. Keep the fish on ice (0-2 °C) until just before filleting. Filleting knife sharpness test: cuts through a sheet of paper without pressure.

HACCP: never use fish with glazed eyes, brown gills, or limp texture. Report to the supplier and discard.
2

Prepare the workstation

Use a blue cutting board (NVWA colour-coding system: blue = fish). Sanitise the filleting knife in water of at least 82 °C for 15 seconds OR with 70% alcohol solution. Place the fish on a damp cloth to prevent slipping.
3

First cut (dorsal side)

Lay the salmon on its side. Make a cut directly behind the head down to the spine (felt via the knife). Turn the knife 90° and cut along the spine from head to tail, angling the knife slightly upward to follow the bones. Use long, fluid strokes. (CIA Professional Chef, Wiley, 2011)
4

Second cut (belly side)

Turn the fish over. Repeat the procedure on the other side. The second fillet releases more easily because the bones are already exposed. Check that all rib bones have come free.
5

Pin bone removal

Feel with your fingertip along the centre of the fillet (lateral line): the pin bones protrude slightly. Grip each pin bone with fish bone tweezers and pull in the direction of the head. Never sideways: that tears the fish flesh. Salmon has 30-35 pin bones per fillet.

Always pull in the direction of the head (forward), never sideways.
6

Anisakis inspection

Hold the fillet up against a lamp or light box (candling). Anisakis worms are visible as 2-3 cm long, spiral-shaped, transparent to white structures. Remove visible worms including a 2 cm margin around them. In cases of heavy infestation: discard the entire fillet.

HACCP: EU 853/2004 requires visual Anisakis inspection when filleting wild fish. If in doubt: freezing at -20 °C for 24 hours destroys all Anisakis larvae.
7

Portioning and refrigeration

Portion the fillet by weight. Cover immediately with cling film and store at 0-2 °C. Label with use-by and re-chilling date. Process bones and head immediately for fumet or discard.

HACCP: store fillets within 2 hours of filleting at 0-2 °C or on ice. Record the filleting date and storage duration in the HACCP log.

HACCP: Anisakis, knife sanitisation, and cross-contamination

Anisakis spp. in wild fish

Anisakis is a parasitic roundworm found in wild fish, particularly herring, mackerel, salmon, squid, and cuttlefish. EU Regulation 853/2004, Annex III, Section VIII requires food businesses to carry out a visual inspection for visible parasites when filleting fish.
Prevention: freezing at -20 °C for a minimum of 24 hours (or -35 °C for 15 hours) destroys all Anisakis larvae. Farmed fish has significantly lower Anisakis contamination than wild fish.
For raw fish preparations (tartare, sashimi, carpaccio): freezing is legally mandatory as a preventive measure (EU 853/2004). This is not a recommendation but a HACCP requirement.

Source: EU Regulation (EC) No 853/2004, Annex III Section VIII; NVWA Anisakis in fish (nvwa.nl)

Knife sanitisation and cross-contamination

When switching between products (meat to fish, red meat to poultry): always sanitise the knife. NVWA guideline: 15 seconds in water of at least 82 °C, OR 70% alcohol spray combined with wiping dry.
NVWA colour-coding system for cutting boards: red for red meat, yellow for poultry, blue for fish, green for vegetables. Never use a yellow board for fish.
EU 853/2004 requires physical separation of fish and meat processing areas or a certified cleaning protocol between operations.

Source: NVWA Colour-Coding System (2023); EU Regulation 853/2004

Temperature requirements for boning and filleting (EU 853/2004)

Product	Max. storage temp. during processing	Max. time outside refrigeration	NVWA guideline
Fresh meat (beef, lamb)	4 °C or below	20 minutes	Return to refrigeration after 20 min on the cutting surface
Poultry (whole, fillet)	4 °C or below	20 minutes	Poultry carries a higher Salmonella risk
Fresh fish (round fish)	0-2 °C on ice	10 minutes	Keep fish on an ice bed during filleting
Fresh fish (flatfish)	0-2 °C on ice	10 minutes	Cover and refrigerate immediately after filleting

Source: EU Regulation (EC) No 853/2004, Annex III, Section V (meat) and Section VIII (fish); NVWA temperature guidelines

Food cost: yield calculation as a competitive advantage

Whole chicken versus chicken breast: a whole chicken costs EUR 3-4/kg, ready-to-use chicken breast EUR 8-12/kg. With in-house boning at 55% yield: chicken breast cost = EUR 3.50 / 0.55 = EUR 6.36/kg usable meat. Time investment: 5-7 minutes per chicken. At 20 chickens per service: 2 hours of extra preparation, savings of approximately EUR 35-65 per day. Always factor in labour costs.
Salmon fillet yield: wild salmon (whole fish) approximately EUR 9-14/kg, ready-to-use salmon fillet EUR 18-25/kg. At 58% yield: in-house fillet cost = EUR 11 / 0.58 = EUR 18.97/kg. Using bones and head for salmon fumet (value EUR 2-3/litre) significantly improves the effective yield.
Sole yield: 45-50% fillet yield makes sole one of the most expensive fish portions relative to purchase weight. Whole sole (bone-in) EUR 12-18/kg: in-house fillet cost = EUR 12 / 0.47 = EUR 25.53/kg for four small fillets. ALWAYS compare labour costs against the price of pre-filleted sole from your supplier.

Frequently asked questions

What is the difference between tunnel boning and seam boning?

Tunnel boning: the bone is removed through a small opening while the meat remains intact like a "sock". This is the method for ballotines and galantines of poultry. Seam boning: boning along the natural boundaries between muscle groups. The meat separates into individual muscle groups that can be portioned directly. Seam boning offers more flexibility for farces, roulades, and portioning. (CIA Professional Chef, 9th ed., Wiley, 2011)

How do I remove pin bones from salmon?

Feel with your fingertip along the centre of the salmon fillet (the lateral line): the pin bones are felt as small ridges. Use fish bone tweezers and always pull in the direction of the head (forward) to avoid tearing the fish flesh. Salmon has 30-35 pin bones per fillet. Alternative: cut a V-notch along the lateral line to remove the pin bones as a block. (Le Cordon Bleu, Fish & Shellfish Masterclass, 2005)

What is the Anisakis risk and when is freezing mandatory?

Anisakis spp. is a parasitic roundworm found in wild fish. EU Regulation 853/2004 stipulates that freezing is mandatory as a preventive measure for raw, lightly cooked, or marinated fish preparations: -20 °C for 24 hours, or -35 °C for 15 hours. This applies to sashimi, tartare, ceviche, and insufficiently heated smoked fish. Farmed fish has significantly lower risk but is not entirely free.

How do I fillet a flatfish (sole, halibut)?

The four-fillet method (Escoffier, 1903): (1) cut along the centre line from head to tail, down to the central bone bed; (2) cut along the edge of each fillet and lift the fillet from the bones with small flat strokes; (3) four fillets per fish. Flatfish has a central bone bed as a guide: the knife follows this bone bed. Sole yield: 45-50%; halibut: 55-60%.

How do I calculate yield for my food cost?

Yield % = weight after boning / weight before boning x 100. Cost per kg of usable meat = purchase price per kg whole weight / yield factor. Example: salmon EUR 11/kg whole, 58% yield: EUR 11 / 0.58 = EUR 18.97/kg fillet. Always compare this against the purchase price of ready-to-use fillets including labour costs for your specific situation.

Which knife do I use for boning versus filleting?

Boning knife: 15-20 cm long, flexible or stiff depending on the product. Stiff knife for beef and lamb. Flexible knife for poultry (follows bone contours). Filleting knife: 20-25 cm, thin and very flexible to follow the bone structure. A filleting knife is too flexible for boning meat. For fish: a dull knife pulls and tears the delicate fish flesh; a sharp knife is mandatory.

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Informational disclaimer

The information on this page is intended solely for educational and informational purposes for hospitality professionals. KitchenNmbrs B.V. strives for accuracy and timeliness but cannot guarantee that all information is fully correct, complete or up-to-date at all times. Culinary techniques, scientific insights and food safety guidelines may change.

Professional responsibility

Applying the techniques described requires professional expertise and training. KitchenNmbrs is not liable for damage, injury, illness or loss resulting from the application of information from this website without adequate professional guidance or verification. Every kitchen, every product and every environment is different: always apply your own professional judgement.

Food safety & HACCP

The HACCP guidelines, temperatures and storage advice on this page are based on Codex Alimentarius (WHO/FAO) as the global baseline standard and EU Regulation 852/2004. Local laws and regulations may differ. Always consult your national food safety authority for the applicable standards in your region:

Netherlands: NVWA (nvwa.nl)
Belgium: FAVV (favv-afsca.be)
Germany: BfR (bfr.bund.de)
United Kingdom: FSA (food.gov.uk)
United States: FDA (fda.gov) — FDA Food Code
EU general: EU Regulation (EC) 852/2004 on food hygiene
International: Codex Alimentarius CAC/RCP 1-1969 (revised 2020)

Allergens & dietary information

Allergen information is indicative. When in doubt about allergens in preparations, always contact the supplier or a certified allergological adviser. KitchenNmbrs accepts no liability for allergic reactions or diet-related harm.

Copyright & sources

All sources mentioned (Escoffier, McGee, CIA Professional Chef, etc.) are the property of their respective publishers and authors. KitchenNmbrs cites these works in accordance with fair use for informational purposes. The source attribution at the bottom of each technique page is not a complete bibliography but an indication of primary sources consulted.

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To the extent permitted by law, KitchenNmbrs B.V. disclaims all liability for direct or indirect damage arising from the use of information on this page. This includes but is not limited to: financial damage from incorrect cost price calculations, damage from food safety incidents, and damage from technical errors or unavailability of the website. The information on this page does not replace professional culinary advice or legal advice.

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Sources and legal information

CIA (Culinary Institute of America) — The Professional Chef, 9th edition (Wiley, 2011)
Le Cordon Bleu — Fish & Shellfish Masterclass (Carroll & Brown, 2005)
Auguste Escoffier — Le Guide Culinaire (Flammarion, 1903; reprint Wiley, 2011)
EU Regulation (EC) No 853/2004 — Annex III, Section VIII: hygiene for fishery products
NVWA — Anisakis in fish: risks and prevention (nvwa.nl)
NVWA — Colour-coding system for cutting boards in the hospitality industry (2023)