The red liquid you see isn't actually blood, but a protein-rich liquid called 'purge'.
Understanding the Red Liquid
Many people believe the reddish liquid that seeps from their steak, especially when raw or medium-rare, is blood. However, this is a common misconception.
Based on scientific understanding, that blood-like liquid is what scientists call "purge". This purge is primarily a combination of water and meat proteins that naturally drain from the muscle tissue.
It's one of these specific proteins, water-soluble myoglobin, that gives the water its red or dark pink colour. This is the same protein responsible for the reddish pink colouring of the meat itself.
Think of myoglobin as a protein within the muscle tissue that holds oxygen, much like hemoglobin does in blood, but it stays within the muscle cells. When meat is cut or stored, this myoglobin, along with water and other proteins, can seep out, forming the purge.
Myoglobin vs. Hemoglobin (Blood)
It's important to distinguish between myoglobin and hemoglobin:
| Feature | Myoglobin | Hemoglobin |
|---|---|---|
| Location | Primarily in muscle tissue | Primarily in blood cells |
| Function | Stores oxygen in muscles | Transports oxygen in blood |
| Colour | Gives meat its red colour | Gives blood its red colour |
| Found in | "Purge" liquid from meat | Circulating in the bloodstream |
Animals are typically drained of most of their blood during processing. Therefore, the liquid you encounter in packaged meat or on your plate is overwhelmingly myoglobin-rich purge, not residual blood.
Why Does Some Steak Have More "Purge"?
Several factors can influence the amount of purge you see:
- Type of Meat: Different muscles contain varying amounts of myoglobin. Beef typically has more myoglobin than pork or chicken, appearing redder and potentially producing more purge.
- Cut of Meat: Certain cuts may release more liquid than others.
- Handling and Storage: Freezing and thawing meat can break down cell walls, causing more myoglobin and water to leak out. Packaging methods also play a role; vacuum-sealed meat often has more visible purge accumulated in the bag.
- Age of the Animal: Meat from older animals tends to have more myoglobin, resulting in a deeper red colour and potentially more purge.
Practical Tips Regarding Purge
- Pat it Dry: Before cooking, patting your steak dry with paper towels can help achieve a better sear, as excess moisture on the surface can steam the meat instead of browning it.
- Don't Discard: While excess purge can affect searing, the liquid itself is not harmful. It's part of the natural composition of the meat.
- Storage: Store meat properly in the refrigerator or freezer to maintain quality and minimize excessive moisture loss before cooking.
Understanding that the red liquid is purge, rich in myoglobin, clarifies why your steak appears "bloody" without actually containing significant amounts of blood. It's a natural characteristic of fresh meat.
