Most people look for bright red steaks at the grocery store, thinking that the bold crimson color indicates freshness. Other carnivores prefer their steak cooked on the rare side, so full of juicy goodness that it’s still bloody.
However, in both cases, the red you’re seeing in your uncooked or barely cooked steaks is not actually blood. It’s myoglobin, a protein that delivers oxygen to an animal’s muscles. The protein turns red when meat is sliced, or exposed to the air. Heating the protein turns it darker. So rare meat isn’t “bloody,” it’s just cooked to a lower temperature. Older animals and animals with more active muscle tissues have meat with more myoglobin.
Some juicy tidbits about steak:
- A packaged steak that appears brownish in color isn’t necessarily bad. After a few days, myoglobin molecules oxidize and the meat turns brown. It may look less appealing, but it’s still safe to eat. In fact, some meat producers treat their meat with carbon dioxide gas to lock in this red color far beyond its normal lifespan.
- A freshly-cut slab of cow’s meat is actually purplish in color.
- The U.S. Department of Agriculture (USDA) recommends cooking steak to an internal temperature of at least 145 degrees Fahrenheit (63 °C) and then letting it rest for three minutes to kill any bacteria that could make you sick.