01. Judging Meat Doneness

The two parts of a muscle—muscle fiber and connective tissue—cook differently. As meat heats, the protein in the muscle fibers becomes firmer and more opaque, and the collagen in the connective tissue melts. We can use either of these changes to determine the doneness of a piece of meat, and the one you use depends on the meat you’re cooking.

Tender meat tends to have very little connective tissue. Most steaks are soft enough to bite into when raw, which allows us to judge their degree of doneness solely on the changes that happen to the protein in the muscle fibers as they heat. Raw meat protein is wet, translucent, brightly colored, and soft. As it gets warmer it becomes drier, more opaque, browner, and firmer. The hotter the meat gets, the more these physical changes manifest themselves, which allows us to equate the look and feel of a piece of cooked meat with specific temperatures. For instance, at 120° to 125°F, the center of a porterhouse steak is juicy, bright red, glistening, and tender; we call that rare. At 135° to 140°F, the center is moist, pink, matte, and resilient; we call that medium-done. Raise the interior temperature to over 165°F and the meat becomes dry, tan, dull, and firm—in other words, well-done.