How to Cook the Perfect Steak (with Science)
A steak cooking on the grill.
Credit: Stephen Mcsweeny , Shutterstock

A perfect steak is a tasty centerpiece to an impressive meal. Fortunately, science can help make this dinner delicious.

The ideal steak is a matter of taste, but proper cooking involves balancing a high external temperature with a lower internal temperature. Getting the balance right ensures that the steak is tender and juicy on the inside, and browned and flavorful on the outside.

"It really is a game of temperatures," said Jeff Potter, author of "Cooking for Geeks: Real Science, Great Hacks and Good Food" (O'Reilly Media, 2010).

Safe steak

"Steak" describes a cut of meat cut perpendicular to the muscle fibers, and typically refers to beef. Steaks can come from different areas of the cow: Chuck steak, for example, comes from the shoulder, sirloin from the cow's back, near the rear. T-bone and porterhouse are cut from the short loin, along the animal's side.

Steaks can be safely eaten with less cooking than ground meat, in most cases, said Ben Chapman, a professor of food safety at North Carolina State University. Ground beef or hamburger mixes surface meat — where nasties such as E. coli can thrive — with internal meat. The U.S. Department of Agriculture recommends cooking all ground beef to an internal temperature of at least 160 degrees Fahrenheit (71 degrees Celsius). [Top 7 Germs in Food that Make You Sick]

Pathogens can't penetrate the internal muscle tissue of a steak, so cooking it rare is low-risk, Chapman told Live Science. That's true unless the steak has been needle- or blade-tenderized, methods that involve puncturing the steak to break up toughness. In those cases, pathogens from the outside of the steak can end up inside. Meat plants are required to label needle- and blade-tenderized meat if they're federally inspected, but not if they're state-inspected or if the tenderizing is done at a grocery store. For that reason, the U.S. Department of agriculture recommends cooking steak to an internal temperature of 145 F (63 C).

If, like Chapman, you prefer rare or medium-rare steak that is cooked less thoroughly, you can always query your butcher.

"I ask specifically, 'Has this been needle-tenderized or blade-tenderized?'" Chapman said. "If I hear that is has been, I don't buy it."

Cooked to perfection

But back to that game of temperatures. The reason meat changes texture, color and taste when it cooks is that proteins in the muscle tissue denature, or change shape. There are different proteins that make up muscle tissue, including myosin, which plays an important role in muscle contraction, and actin, which is also involved in muscle contraction as well as cell division and other functions.

Myosin starts to denature around 120 to 130 F (49 to 55 C), Potter told Live Science. Actin denatures around 150 F (66 C).

For taste, "it seems we prefer when myosin is denatured and actin is in its native state," Potter said.

On the outside, though, the perfect steak is browned. Browning occurs because of the Maillard reaction, a chemical reaction in which sugars and amino acids in the meat react and create new, flavorful compounds. (The same reaction occurs when you toast bread.) To get a Maillard reaction, the surface temperature of the steak needs to be around 350 degrees F (177 degrees C), Potter said. (An infrared thermometer can give the temperature of surfaces, he added.) Some people advocate salting steak and letting it sit to pull moisture off the surface and hasten this Maillard reaction. Most likely, the small amount of liquid pulled out of the steak by the salt won't make a huge difference in cooking time. Letting salt sit for a time on the meat might allow the seasoning to penetrate the outer layers, however, creating a more flavorful experience overall.

Balancing high heat on the outside with low heat on the inside is a skill on the grill. The truly dedicated and precise can try a different technique: sous-vide. Sous-vide is a French method that uses immersion in water to poach food at a low temperature. The cooked meat can then be seared over high heat to finish it off.

Sous-vide works well to cook perfect steak, Potter said. But there's another side of cooking, too.

Most of the time, "I'm probably just going to throw a steak into a hot cast-iron pan or on the grill outside," Potter said. "That's a little more fun."

The perfect steak is a matter of taste, and Potter recommends experimenting to see what your palate prefers. Here are the basic steps for steak perfection:

1. Choose a cut with plenty of fat and thickness. Fat equals moisture, and no one wants a dry steak.

2. If you want to salt your steak, let the salt sit on the meat for a minimum of 40 minutes (you can salt your steak even several days in advance, if you prefer). This allows the salt to dissolve into the meat. Pre-salting steak is controversial in the cooking world, so feel free to experiment. 

3. From here, it's a game of heat. The internal temperature of a rare steak is 130 F (54 C). For medium-rare, aim for 135 F (57 C). To cook to medium, aim for 145 F (63 C). Finally, medium-well takes about 160 F (71 C). Take the steak off the grill 5 F (3 C) below your target, as the surface will heat the interior slightly even after the meat is off the grill.

Don't worry about searing first to "lock in juices." Steam (aka moisture) is perfectly capable of escaping through seared meat as well as partially cooked meat. You do want to finish with a flourish of high heat, though, to create those crusty Maillard reactions.

Another myth about steak is that you shouldn't flip it too often, lest it become tough. No truth there. Flipping a steak multiple times can help it cook more evenly, Potter said.

4. Let the meat rest for a few minutes after you cook it. If the liquids inside the steak cool slightly before you cut the meat open, they will be more viscous, meaning they're less likely to flow all over your plate — or burn your tongue. Win-win.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.