A Bloody Steak
I came across this statementt in a "how to" cook a steak on a gas grill,
".... Then flip with tongs, not a fork. Don't poke any holes in your steaks at this stage because the liquids inside are under pressure from the high heat and you can lose valuable juices. By the way, those juices are myoglobin, a protein liquid found in the muscles, and they are not blood. Blood is drained during slaughter. Tell that to your squeamish teenagers."
It sure looks like blood!!!
I've had various styles of blood sausage, Mexican, Korean, French. I've also bought a cube of cooked blood from an Asian grocery. I haven't yet bought a tub of frozen blood, which could be used to make my own sausage, or flavor a soup or stew. From what I've read the frozen blood is treated with salt or something to prevent coagulation, though you may still have to break up gelled clumps. In all these forms blood is quite dark, almost black (hence the name black pudding).
Myoglobin is related to hemoglobin, which is the chemical that makes blood red. Myoglobin changes color as it is heated, which is why color is one indicator of how well-done beef is. Note that a common criteria for properly cooked chicken and hamburger is that the juices run clear - i.e. about 165deg.
Which raises the question - why is beef darker than pork or chicken? Apparently it is the myoglobin concentration.
"The main determinant of the nutritional definition of the color of meat is the concentration of myoglobin. The white meat of chicken has under 0.05%; pork and veal have 0.1-0.3%; young beef has 0.4-1.0%; and old beef has 1.5-2.0%."