What’s That Red Juice in Steak?
- ryanwu245
- Jul 22
- 2 min read
Picture this: you’ve let your rosemary butter-basted cut of New York strip rest for 10 minutes, and you’ve made sure with a thermometer that it achieved a 130°F internal temperature to get that perfect medium rare. When you cut into the steak you’ve so meticulously cooked, you feel a sense of disappointment and disgust when you see a pool of red liquid oozing from the exposed bit of pink flesh.
You think to yourself, is that blood? You start questioning why people even like medium-rare steaks. You’ve contained your skepticism of non-well-done steaks and their seemingly uncooked, vivacious rosy insides for now, but you start thinking about how eggplant steaks might not be so bad after all.
But fear not! That red liquid isn’t blood, but actually a mixture of water and a protein called myoglobin. You may have noticed that myoglobin sounds a lot like hemoglobin, the protein in our red blood cells that transport oxygen throughout our body. Myoglobin serves a similar purpose: storing oxygen in muscles to provide energy.
A lot of myoglobin is found in slow-twitch muscle, AKA red/dark meat. Slow-twitch muscles are used for extended activity, such as standing or walking, which requires a constant energy supply in the form of oxygen. Myoglobin is what gives red meat its color. As steak is cooked, myoglobin denatures (loses its shape) and shifts the color of the meat from red/pink to tan/brown.
In contrast, fast-twitch muscles like chicken breast take on a white color when cooked. Myoglobin is relatively absent in these areas, as these fast-twitch muscle fibers are used for quick bursts of activity like fleeing from danger.
Well, what about the water? In muscle tissue, about 75% of each cell is water. When meat is frozen, whether it be during transportation or storage, ice crystals puncture cell membranes and let water and myoglobin leak out.
You can also be sure that the red liquid isn’t blood because almost all blood is drained out when livestock are slaughtered. So the next time someone tries to order a well-done steak, tell them there’s nothing to worry about other than some extra protein in the sauce!
Ryan Wu is a rising junior at Hunter College High School in New York, New York. He has participated in the highly selective Science Honors Program at Columbia University since 2024, where he studied university-level topics such as immunology, toxicology, bioengineering, and biotechnology. He currently serves as the layout editor and writer for EATS Food Magazine.
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