Doneness & Temps

Beef Doneness

Beef: Blue (Bleu)

Also: bleu, blue rare, Pittsburgh rare, very rare, saignant-bleu

The most minimal intervention: a hot sear produces a dark crust while the center remains cool, nearly raw, and deep purple-red.

Blue, or bleu in French culinary tradition, is the stage below rare. The steak is cooked only long enough for the exterior to develop a seared crust — typically 30 to 60 seconds per side over extreme heat — while the center temperature stays between 46°C and 49°C (115–120°F). The interior is cool to the touch when cut, purple-red in color, and has the yielding, almost raw texture of fresh beef. It is a classical stage in French bistro cooking and remains popular among aficionados who prize unadulterated beef flavor.

In photos

Beef: Blue (Bleu) at 46–49°C (115–120°F). Below 50°C, myosin begins to denature but actin remains fully intact, so the muscle fibers retain the same soft, slippery structure as raw beef. Visual cues: Deep purple-red center, virtually indistinguishable in color from raw beef, Cool or barely warm core when pressed or cut, Exterior crust is dark brown and fully seared.
Beef: Blue (Bleu) at 46–49°C (115–120°F). Below 50°C, myosin begins to denature but actin remains fully intact, so the muscle fibers retain the same soft, slippery structure as raw beef. Visual cues: Deep purple-red center, virtually indistinguishable in color from raw beef, Cool or barely warm core when pressed or cut, Exterior crust is dark brown and fully seared.
Beef: Blue (Bleu) in context — the stages just below and above, side-by-side. Blue, or bleu in French culinary tradition, is the stage below rare. Target reference 46–49°C (115–120°F).
Beef: Blue (Bleu) in context — the stages just below and above, side-by-side. Blue, or bleu in French culinary tradition, is the stage below rare. Target reference 46–49°C (115–120°F).
Beef: Blue (Bleu) in practice — Entrecôte bleu (French bistro classic). The American 'Pittsburgh rare' or 'Pittsburgh style' is a close cousin: the steak is charred black on the exterior (often on a very high-heat grill or in a screaming-hot cast-iron) while the center remains bleu or just barely rare.
Beef: Blue (Bleu) in practice — Entrecôte bleu (French bistro classic). The American 'Pittsburgh rare' or 'Pittsburgh style' is a close cousin: the steak is charred black on the exterior (often on a very high-heat grill or in a screaming-hot cast-iron) while the center remains bleu or just barely rare.

What happens

Below 50°C, myosin begins to denature but actin remains fully intact, so the muscle fibers retain the same soft, slippery structure as raw beef. Collagen is entirely unchanged. The Maillard reaction occurs only at the surface, where contact with a pan or grill above 150°C generates the aromatic crust. Intramuscular fat does not render at this temperature, so the interior retains full fat globule structure. Moisture loss is negligible — well under 5% — giving bleu steaks their characteristically wet, glossy cut surface.

What to look for

  • Deep purple-red center, virtually indistinguishable in color from raw beef
  • Cool or barely warm core when pressed or cut
  • Exterior crust is dark brown and fully seared
  • Flesh yields with almost no resistance under thumb pressure
  • Glossy, wet interior surface when sliced
  • Aroma is dominated by the sear; the interior smells of fresh beef

How to check

  • Instant-read thermometer inserted horizontally into the thickest part should read 46–49°C (115–120°F)
  • Press test: the steak feels soft and offers no spring, similar to the fleshy base of a relaxed thumb
  • Cut test: center is purple-red and cool — not warm pink
  • Time guide only for uniform-thickness steaks: 30–45 seconds per side on a very hot cast-iron or grill

Food safety

Bleu/blue is well below any food-safety threshold for whole-muscle beef. The USDA recommends 63°C (145°F) with a 3-minute rest for intact beef cuts. Whole-muscle steaks are surface-contaminated only, so searing the exterior does address the primary risk — but the center remains raw. This stage is not appropriate for ground beef, mechanically tenderized (blade-tenderized or needle-tenderized) cuts, or immunocompromised individuals.

Carryover & resting

Carryover is minimal at bleu because the core temperature is so far below the sear temperature, but even 1–2°C of carryover can push it toward rare. Rest on a warm plate for no more than 60 seconds; longer resting will elevate the center temperature noticeably.

The science behind it

  • Rare

    The next doneness stage up; center reaches 52°C and turns bright red-pink

  • Maillard Reaction

    The surface browning that defines the crust even when the interior is barely heated

  • Myosin denaturation

    Begins around 50°C — at bleu this is barely initiated, preserving raw texture

  • Resting

    Keep rest time short at bleu to prevent carryover from nudging the steak into rare

Appears in

Entrecôte bleu (French bistro classic)Faux-filet bleuCôte de bœuf bleuPittsburgh rare ribeye (bleu interior, heavily charred crust)

References

  1. 1.On Food and Cooking — Harold McGee
  2. 2.The Fat Duck Cookbook — Heston Blumenthal
  3. 3.Modernist Cuisine: The Art and Science of Cooking — Myhrvold, Young, Bilet
  4. 4.Larousse Gastronomique (2009 edition)

Confidence: high

Notes

Pittsburgh Rare

The American 'Pittsburgh rare' or 'Pittsburgh style' is a close cousin: the steak is charred black on the exterior (often on a very high-heat grill or in a screaming-hot cast-iron) while the center remains bleu or just barely rare. The term is said to originate from steelworkers in Pittsburgh who cooked meat on the hot metal of their equipment.

Selecting the right cut

Bleu is best suited to tender, well-marbled cuts with minimal connective tissue — ribeye, sirloin, fillet, and strip steak — where the raw-textured interior is an asset rather than a liability. Tougher cuts (chuck, brisket) that require long cooking for collagen breakdown are wholly unsuitable.