When purchasing red meat, including steaks, many grocery shoppers often find red liquid in the bottom of the packaging, which you probably assumed was blood.

It turns out, it’s not actually blood, but rather a protein called myoglobin, according to Buzzfeed. The protein is what gives the meat and its juices a red hue, and it’s perfectly normal to find in packaging.

Can’t say for a fact that packaged Costa Rica beef is full of the red liquid, but a safe bet that the packaged USDA choice beef found at Masxmenos and Walmart stores is.

Similar to the hemoglobin found in our blood, myoglobin carries oxygen to the animal’s muscles, according to the New York Times. The protein changes color when it’s exposed to air and heat, which is why your meat transforms from red to brown when it’s cooked or sits in packaging for too long.

What’s more, the red juice that oozes from your medium-rare steak isn’t blood, either. It’s the same protein found at the bottom of your packaging, according to The Huffington Post. Rare steaks and burgers aren’t exposed to heat for as long as well-done meats, causing more red myoglobin to be present.

After a few days in a grocery store display case, myoglobin molecules naturally oxidize and the meat eventually turns brown. But brown does NOT mean it’s bad. It may look less appealing, but it isn’t any less safe to eat. If you buy brown meat, just be sure to cook it right away, because it’s likely already been out there for a few days.

SEOUL, SOUTH KOREA – NOVEMBER 27: An employee prepares imported U.S. beef at a store on November 27, 2008 in Seoul, South Korea. The import of U.S. beef, which is sixty to seventy percent cheaper than Korean beef, had been suspended for 13 months due to the discovery of banned backbones in import shipments. (Photo by Chung Sung-Jun/Getty Images)

So the next time someone gawks at your rare and juicy sirloin steak, you can tell them to relax-it’s just protein!

And while you are here, we recently found out that that white gunk on salmon isn’t actually fat, but rather a soluble protein. Or just how a single strip of the cured pork can magically produce an entire panful of fat.