If you’ve ever cut into a rare or medium-rare steak and seen that vivid red juice pooling on your plate, you might have thought, “That must be blood, right?” You’re not alone—this is a widespread belief. For years, many people have assumed that the red liquid seeping out of a juicy steak is blood. But here’s the surprising truth: it’s not blood at all.
So what exactly is it? That red or pinkish juice is actually a mix of water and a protein called myoglobin—and it’s completely harmless.
What Is Myoglobin?
Myoglobin is a protein found in muscle tissue, and its main job is to carry and store oxygen in muscle cells. Think of it as the muscle’s personal oxygen supply. It’s somewhat similar to hemoglobin, the protein in your blood that gives it that deep red color and helps transport oxygen throughout your body. When muscle tissue is exposed to air—like when a steak is cut or cooked—the myoglobin reacts with oxygen and gives off that reddish-pink color.
The amount of myoglobin varies depending on the animal and the type of muscle. Beef, for example, contains more myoglobin than chicken or pork, which is why steak appears redder and richer in color compared to white meats.
Why Isn’t It Blood?
By the time meat makes its way to your kitchen or restaurant plate, almost all of the actual blood has been drained during the slaughtering and butchering process. Meat is made up of muscle tissue, and while it does contain small blood vessels, most of the blood is removed early in processing. What remains in the muscle fibers is primarily water and myoglobin—not blood.
So, when you see that “bloody” liquid oozing out of your steak, you’re really just seeing water tinted red by myoglobin, not leftover blood. And that’s an important difference.
Why Rare Steaks Appear So Red
If you’ve noticed that rare and medium-rare steaks seem much juicier and redder than well-done ones, there’s a scientific reason for that. Myoglobin is temperature-sensitive. When meat is cooked at lower temperatures, the myoglobin remains intact, retaining its reddish hue. As the internal temperature of the meat rises, the myoglobin begins to break down and lose its color, turning brownish-gray—which is why well-done meat doesn’t “bleed” or look red.
Here’s a breakdown:
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Rare steak (cool red center): Myoglobin remains mostly intact, resulting in bright red juice.
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Medium steak (warm pink center): Some myoglobin is broken down, but there’s still a pinkish tint.
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Well-done steak (no pink): Most or all of the myoglobin has been denatured, resulting in little to no red or pink liquid.
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