Many people think that when they sear a piece of meat (that is, brown the outside of it using a high temperature), they are creating a protective crust that locks in the meat’s juices. But this is completely untrue, says Harold McGee, author of On Food and Cooking: The Science and Lore of the Kitchen.
“Your ears and eyes will tell you every time that searing doesn’t seal in the juices,” says McGee. “The sizzling sound comes from the constant flow of moisture from the meat onto the hot pan, where it’s vaporized. Turn the meat to cook the other side and you see juices seep through the seared side, and rest the meat afterwards and it leaks juices onto the plate.”
McGee says the juiciness of cooked meat is just a result of time cooked: Rare steak is juicier than well-done steak. He also says that well-marbled meat seems moister than a lean cut if cooked to the well-done stage because the fat will melt and “permeate” the meat while it’s cooking.
Does this mean you shouldn’t bother searing? No, but sear for the right reason: to develop flavor. When you brown meat it causes a reaction that forms the compounds we associate with “nutty, meaty, roasted, toasted, burnt, or caramel” flavors, says Jason Behrends, a spokesperson for the Institute of Food Technologists and research professor in the Mississippi State University Department of Food Science, Nutrition, and Health Promotion. In other words, searing helps create a tasty steak or burger.