The Science of Cooking Proteins
The primary goals when cooking meats and poultry is to develop flavor, tenderness, and juiciness. Because these products are a major part of the food budget, a secondary goal, but no less important, is to enhance their cooked yield. Animal proteins are made up mostly of water, so the length of cooking time and the temperature of the cooking medium will affect their final outcome. Cook them too much or too long and they will become tough and dry, plus their yield will be greatly diminished. Optimizing the cooking process will preserve the quality and integrity of the product, without excessive moisture loss or shrinkage.
Meat is made up of proteins in the form of muscle fibers, or strands, that are bundled and held together with connective tissue. Fat is dispersed in and around the muscle fibers. Connective tissue, in the form of tendons, harnesses the muscles together in bundles to the bone structure.
Connective tissue, a form of protein, is divided into elastin and collagen. Elastin is found in ligaments that bind bone-to-bone in joints and is also found in blood vessels. Elastin, also called silver skin, does not break down in the cooking process and is usually removed mechanically in the butchering process. Collagen is a protein that will melt into gelatin when cooked and provides flavor and mouth feel to meat.
Equally important in the muscle fiber structure are smaller bundles, called fascicles, that determine the grain and tenderness of the muscle. Fascicles are wrapped in collagen. Meats from lightly exercised muscles, like a beef tenderloin, will appear fine grained and feel smooth in texture. Fascicles from muscles that are exercised more, for example from a beef brisket, will appear larger and have a coarser texture. According to the Encyclopedia of Meat Sciences, studies have shown a correlation between the fascicle grain and tenderness.
Tenderness versus Flavor
We often use tenderness as a description of quality when eating meats and poultry. Tenderness in meat has to do with several factors including the age of the animal, the amount of marbling (or intramuscular fat), where the cut comes from on the animal, and of course, the cooking method. Fish and seafood, with a few exceptions like squid and octopus, are naturally tender because of their low connective tissue.
Tenderness does not always equate to flavor. Flavor is derived mostly from fat in the animal. A tenderloin steak implies that it is tender, however this cut lacks the flavor of an abundantly marbled T-bone steak. Flavor and tenderness come together in different ways in the preparation process. Some cuts of meat will have good flavor and juiciness through natural marbling while others will be leaner and dryer. For those leaner cuts of meats that can be dry and lacking in flavor, brining, larding, and barding are ways to add flavor and moistness during the preparation process.
The Cooking Process
Animal proteins when raw are relaxed and soft, but as they are heated the proteins begin to coagulate and squeeze together pushing out moisture. The higher the temperature a protein is cooked, the tighter and firmer it becomes, while at the same time expelling moisture. This expulsion of moisture causes the proteins to contract, toughen, and eventually dry out. As the proteins continue to cook for a prolonged length of time, they eventually start to break down and become tender again, as in the case of a braise or a stew.
Basic Cooking Methods for Proteins
Since livestock animals have similar skeletal and muscle structures, it makes sense that cooking methods are the same for corresponding cuts. For example, loin and tenderloin cuts, whether from beef, veal, or lamb, are naturally tender and require minimal cooking. The variables will be in the temperature and length of cooking time because of the size of the cuts.
Poultry too, whether from chicken, turkey, or duck, have similar characteristics in skeletal and muscle structure, and can be cooked. In these animals the breast meat tends to be lean, tender, and dryer if cooked too much, while the legs and thighs have more connective tissue and fat making them a little tougher but more flavorful and juicier.
What Cooking Method to Use?
Cook minimally and use dry heat (the most common method) by grilling, sautéing, and roasting or moist heat methods including poaching and sous vide.
Cook longer and slower with a lower temperature using braising, stewing, simmering, sous vide and barbecuing methods.
Doneness for meat, poultry, fish, or shellfish, is determined by the species, the individual cut, and the desired outcome (usually based on palatability). Small tender cuts of meat, including steaks, chops, and cutlets cooked from rare to well done, are usually tested by the touch method of placing pressure on the surface of the item. These items are cooked to temperatures from rare to well done. The temperature method, gauged with a thermometer, is used for large roasts of meat, poultry, or whole fish, when a desired degree of doneness is required. Tough cuts that are braised, stewed, or simmered are tested by the fork-tender method; when the meat is pierced it will easily slide off the fork.
Touch Method - Steaks, chops and cutlets
Temperature Method –Large roasts and poultry
Tenderness – Tougher cuts that are braised, stewed, barbecued, or simmered