That bright crimson liquid you’re looking at is simply a mixture of water and a protein known as myoglobin. As a result of being exposed to oxygen, the iron contained inside this protein becomes red in color. This mechanism is remarkably similar to the one that hemoglobin does in the human body.
Is the juice in a rare steak blood?
The ‘liquid’ in your steak isn’t blood, as some people believe. To be fair, you might be forgiven for thinking that the reddish liquid that makes a rare steak ″juicy″ is actually blood. After all, we prefer to refer to a rare steak as ″bloody,″ so it’s not a huge leap to believe that the crimson liquid that pours out of your steak when you cut into it is blood.