Connective Tissue

Muscle fibers are bound together in a network of proteins called connective tissue. Each muscle fiber also is covered in a sheath of connective tissue.

It is important for the cook to understand connective tissue for one basic reason: Connective tissue is tough. To cook meats successfully, you should know:

• Which meats are high in connective tissue and which are low.
• What are the best ways to make tough meats tender.

1. Meats are highest in connective tissue if they come from more muscular regions or from older animals.
   • Muscles that are more exercised—muscles in the legs, for example—have more connective tissue than muscles in the back.
   • Meat from a young animal, such as veal, is more tender than meat from a young steer, which, in turn, is more tender than meat from an old bull or cow. (Young animals have connective tissue, too, but it becomes harder to break down as the animal ages.)

2. Meats high in connective tissue can be made more tender by using proper cooking techniques.

   There are two kinds of connective tissue: collagen, which is white in color, and elastin, which is yellow.

   • Collagen.

     Long, slow cooking in the presence of moisture breaks down or dissolves collagen by turning it into gelatin and water. Of course, muscle tissue is about 75 percent water, so moisture is always present when meats are cooked. Except for very large roasts, however, long cooking by a dry-heat method has the danger of evaporating too much moisture and drying out the meat. Therefore, moist-heat cooking methods at low temperatures are most effective for turning a meat high in connective tissue into a tender, juicy finished product.

     Other factors also help tenderize collagen:

     • Acid helps dissolve collagen. Marinating meat in an acid mixture, or adding an acid such as tomato or wine to the cooking liquid, helps tenderize it.
     • Enzymes are naturally present in meats. They break down some connective tissue and other proteins as meat ages (see Aging). These enzymes are inactive at freezing temperatures, slow-acting under refrigeration, active at room temperature, and destroyed by heat above 140°F (60°C).
     • Tenderizers are enzymes such as papain (extracted from papaya) that are added to meats by the cook or injected into the animal before slaughter. Exercise care when using enzyme tenderizers. Too long an exposure at room temperature can make the meat undesirably mushy.

   • Elastin.

     Older animals have a higher proportion of elastin than younger animals.

     Elastin is not broken down in cooking. Tenderizing can be accomplished only by-removing the elastin (cutting away any tendons) and by mechanically breaking up the fibers:

     • Pounding and cubing (cubed steaks)
     • Grinding (hamburger)
     • Slicing the cooked meat very thin against the grain (as in London broil)