The Food Lab: Better Home Cooking Through Science

by J. Kenji López-Alt

a chicken is actually a remarkably simple beast in culinary terms. Its matter can be divided into roughly four different parts: • Muscle is what we think of as the meat on the chicken. It’s the fleshy stuff that twitches and makes the bird go, and it can be further divided into two categories: slow twitch and fast twitch. • Slow-twitch muscles are meant for sustained movement—i.e., the legs and thighs that keep the chicken standing, walking, and bending down or up. Because slow-twitch muscles are aerobic (they require oxygen to function), they are typically dense with capillaries carrying oxygen-rich red blood cells. That’s why they appear to be darker. • Fast-twitch muscles are used for short bursts of intense energy—they’re the muscles that are found in chicken breasts, used to power the wings when a frightened chicken needs to escape from a dangerous situation. Because their activity is anaerobic (they don’t require oxygen to twitch), they tend to be less dense with capillaries, giving them their characteristic pale color. Incidentally, the same distinction between fast- and slow-twitch muscles occurs in pretty much all animals, even humans. Ever wonder why a tuna is deep red while a cod is pale white? Tunas are made almost entirely of all-powerful slow-twitch muscles, which allow the fish to rapidly torpedo their way through the water for long periods of time. A cod moves only when he’s eating or frightened. • Fat provides insulation and energy storage for chickens...