Muscles in the legs, for example, have more connective tissue than muscles in the back. They come from older animals. Meats high in connective tissue can be made more tender by using proper cooking techniques. Collagen Moist heat turns collagen into gelatin and water. Moist heat at low temperatures for a longer time is most effective in creating a tender, juicy finished product.
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. Enzymes are naturally present in meat. They break down some connective tissue and other proteins as meat ages . 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.