tenderness

The tenderness of meat is influenced by several factors, including the grain of the meat, the amount of connective tissue, and fat content. Meat grain refers to the size of muscle bundles; finer grains indicate smaller bundles and more tender meat, while coarser grains mean larger bundles and tougher meat.1

Cooking meat involves structural changes due to heat affecting connective tissue and muscle proteins. Collagen, a connective tissue protein, begins to shrink around 50-71°C (122-160°F) and turns gelatinous above 71°C (160°F). This process, known as gelatinization, can tenderize tougher cuts of meat when cooked slowly under moist conditions. Myofibrillar proteins like actin and myosin lose solubility and begin to toughen between 40-77°C (104-170°F).23

After an animal's death, muscles stiffen due to protein changes, a state called rigor mortis. This stiffness eventually decreases through the enzymatic breakdown of structural proteins, a process called resolution of rigor, which can continue for weeks and is known as aging. This aging process enhances meat tenderness and palatability. For example, filet mignon, cut from the tenderloin, is exceptionally tender because this muscle has few connective tissues and is not heavily used by the animal.45