What is the red liquid in steak? It's not blood.

December 25, 2025 •

4 min read

According to the meat industry, almost all blood is drained from the animal's muscle tissue during the slaughtering process, well before it ever reaches your plate. This means that the red liquid you often see in steak is not blood, but a protein-rich fluid called myoglobin.

Quick Summary

The red liquid in steak is primarily myoglobin, a protein that stores oxygen in muscle cells, mixed with water. Its color changes with heat, explaining why rare steak is red and well-done meat turns brown. Proper meat handling and resting after cooking are key for a juicy, flavorful result.

Key Points

Myoglobin, Not Blood: The red liquid in steak is a protein called myoglobin mixed with water, not blood, which is drained from the animal during processing.
Source of Red Color: Myoglobin is an iron-rich protein that stores oxygen in muscle cells and is responsible for the red color of meat.
Color Changes with Heat: As a steak cooks, myoglobin denatures and changes color, which is why a rare steak is red and a well-done steak is brown or gray.
Juiciness and Flavor: The liquid, known as 'purge' in the industry, carries much of the meat's flavor. Resting a cooked steak is crucial to reabsorb these juices for a moister, more flavorful result.
Temperature Dictates Doneness: The level of doneness in steak is determined by the internal temperature, which directly affects the state of the myoglobin.
Freezing and Thawing: Freezing meat can cause more liquid to leak out upon thawing because ice crystals damage muscle cells, releasing more myoglobin.
Food Safety: While the pink color in whole cuts of steak is normal and safe when cooked correctly, ground meat requires a higher temperature to kill bacteria mixed throughout.

Debunking the Myth: Myoglobin vs. Blood

For many, the sight of a vibrant, crimson liquid oozing from a rare steak can be a bit unsettling, leading to the assumption that they are seeing blood. However, this is one of the most common misconceptions in the culinary world. The truth behind the red liquid lies in basic biology and food processing. The fluid is a mixture of water and myoglobin, a powerful protein found within muscle fibers. The color of myoglobin depends on its oxygenation, changing from a purplish hue to a bright red when exposed to air.

During the butchering process, animals undergo a procedure called exsanguination, which removes the vast majority of the animal's blood. By the time meat arrives at the grocery store or a restaurant, the red fluid we see is purely the combination of muscle-cell moisture and myoglobin. A higher concentration of this protein is what gives red meat its characteristic color, compared to the lower levels found in poultry, for example.

The Science of Myoglobin and Heat

Myoglobin's color changes aren't just for show; they are a direct indicator of how much heat the meat has absorbed. This chemical reaction is the key to understanding steak doneness. As a steak cooks, the myoglobin is denatured by the increasing internal temperature.

Rare: At temperatures around 125-130°F (52-54°C), the myoglobin remains mostly red, resulting in a cool, crimson center and very soft texture.
Medium-Rare: A step up, 130-140°F (54-60°C) yields a warmer red center, with the myoglobin beginning its heat-induced transformation. This is often considered the ideal balance for many steak connoisseurs.
Medium: At 140-150°F (60-65°C), the center turns pink as the myoglobin changes into a new compound called hemichrome.
Well-Done: Beyond 160°F (71°C), the myoglobin completely denatures, turning the meat a uniform brown or gray and expelling most of its moisture.

This process also explains why a steak that has been frozen and thawed may release more liquid. The ice crystals that form during freezing can pierce the muscle cell walls, causing more myoglobin and water to leak out when defrosted.

How to Achieve a Juicy Steak: The Importance of Resting

One of the most crucial steps to ensure a perfectly juicy steak is to let it rest after cooking. This practice directly addresses the myoglobin and water movement within the meat. When a steak is cooking, the muscle fibers tighten and force the internal moisture toward the center. If you cut into the steak immediately after removing it from the heat, all that delicious liquid will spill onto the plate, leaving your meat dry. By allowing the steak to rest, the muscle fibers relax, reabsorbing the moisture and distributing it evenly throughout the cut. The general rule of thumb is to let the steak rest for at least five minutes, or half the cooking time, before slicing.

Comparison of Myoglobin and Hemoglobin


Feature	Myoglobin	Hemoglobin
Function	Stores oxygen in muscle cells for use by muscles.	Transports oxygen in the bloodstream (via red blood cells) from the lungs to the rest of the body.
Location	Found primarily within muscle tissue.	Circulates in the bloodstream.
Molecular Structure	A single polypeptide chain (monomer) with one heme group.	Four polypeptide chains (tetramer), each with a heme group.
Oxygen Affinity	Has a very high affinity for oxygen, allowing it to store a reserve supply.	Exhibits cooperative binding, meaning it binds oxygen more efficiently as more oxygen becomes available.
Color	Responsible for the red color of muscle tissue; turns brown when fully cooked.	Responsible for the red color of blood; drained during processing.

Conclusion: Savor the Flavor, Not the Fear

Understanding what the red liquid in steak is not only enhances your knowledge of food science but also improves your cooking. By embracing the fact that the crimson juice is myoglobin, not blood, you can confidently prepare and enjoy rare and medium-rare steaks without worry. Furthermore, properly resting your meat ensures that this protein-rich fluid is reabsorbed, guaranteeing a more tender and flavorful result every time. The red color is a natural and desirable characteristic of quality red meat, a sign of its rich iron content and ability to hold moisture. So, next time you see that vibrant juice, you can appreciate it as a natural sign of a perfectly cooked, juicy piece of meat.

Health and Safety Considerations

While the red color from myoglobin is not a sign of danger in whole cuts of beef, it's essential to understand the difference when it comes to food safety. The USDA provides clear guidelines for internal temperatures to ensure any bacteria on the surface are killed. For whole cuts of meat like steak, the interior is generally safe, but for ground meat, bacteria can be mixed throughout during processing, requiring a higher cooking temperature. Always use a meat thermometer for accurate results.

Whole Cuts of Beef: Minimum internal temperature of 145°F (63°C) with a 3-minute rest time.
Ground Beef: Minimum internal temperature of 160°F (71°C).

Following these simple guidelines will ensure your perfectly cooked, myoglobin-rich steak is as safe as it is delicious. For additional resources on cooking techniques and food safety, consider visiting the USDA's official website.

Frequently Asked Questions

No, the red liquid often seen in steak packaging is not blood. It is a mixture of water and myoglobin, a protein found in muscle tissue.

Yes, a pink steak can be perfectly safe to eat. The USDA recommends a minimum internal temperature of 145°F (63°C) for whole cuts of beef, followed by a three-minute rest period. At this temperature, the steak's interior may still be pink, but any surface bacteria will have been destroyed.

While both are iron-containing proteins, hemoglobin transports oxygen via the bloodstream, whereas myoglobin stores oxygen in the muscle cells. During processing, hemoglobin (and most blood) is removed.

A well-done steak reaches a high enough internal temperature that the myoglobin denatures completely, causing it to lose its red color and for much of the water to evaporate, resulting in a drier, grayish-brown appearance.

Resting a steak allows the muscle fibers, which tightened during cooking, to relax and reabsorb the internal juices. This prevents the flavorful liquid from spilling out when you cut the steak, ensuring a more tender and juicy result.

Yes, cuts of meat with a higher myoglobin content, like a ribeye, are often darker red and contain more flavor and moisture. Myoglobin and fat are often found together, contributing to the richness of the steak.

Excessive liquid, known as 'purge,' in the packaging can sometimes indicate that the meat has lost a significant amount of moisture due to freezing, thawing, or age. This can lead to a less tender and flavorful steak.