The reddish liquid released from meat during cooking is often mistaken for blood. In reality, it is not blood but a mixture of water and a protein called myoglobin found in muscle tissue.
During the manufacturing process, all blood is removed, and the steak purchased from a trusted retailer is entirely free of it. Indeed, blood tends to coagulate upon exposure to air.
The liquid observed during defrosting or cooking is simply a combination of water and myoglobin, a protein located within muscle tissues. Its role is to capture oxygen from the circulating hemoglobin to replenish it. When these tissues are damaged, the substance is released.
This protein consists of various elements, such as iron, which contributes to its red color and is primarily found in animals that frequently use their muscles. Consequently, horse meat exhibits a deep red hue due to its significantly high myoglobin content, in contrast to the so-called white meats like chicken or turkey.
Source: Quora