Artificial Tenderizing of Meats
Enzymes. One of the reasons that contracted muscles begin to “relax” toward the end of rigor mortis is that proteolytic enzymes work internally to break down the proteins within the muscle fibrils. A more even distribution of enzymes may be achieved by injecting a tendering solution of papain, or some other proteolytic enzyme, into the bloodstream of animals ten minutes before slaughter. This optional treatment sends enzymes traveling to all the muscles through the circulatory system, but they are not activated until meat form the animal is exposed to heat during preparation. This process not only increases tenderness, but shortens the time of rigor mortis and aging.
Commercial meat tenderizers are available for consumers to use, but they are effective only on fairly thin cuts of meat because they penetrate to a depth of only 1/2 to 2 millimeters. They are ineffective on larger cuts such as roasts. Tenderizers are sold as a salt or liquid mixture and differ in the proteolytic enzymes they contain: papain from papayas, bromelin from pineapples, ficin from figs, and trypsin from the pancreases of animal. In home use, these enzymes are sprinkled on meat, which is then pierced with a fork to drive the enzymes below the surface, where they hydrolyze muscle cell proteins and connective tissue when activated by the heat of preparation. The enzymes are not active at room temperature. The optimal activity temperature (highest rate of activity) for papain, the most common tenderizing enzyme is about 131 to 170F which is reached only during heating. Exceeding 185F denatures the enzyme, thus inhibiting its activity. Uniform distribution is hard to achieve with the use of commercial tenderizers, and any attempt to get more of the enzyme to penetrate by adding excessive amounts of it can cause the meat to have an unappetizing, mealy, mushy texture.
Salts. Tenderness can also be increased by the addition of salts in the form of potassium, calcium, or magnesium chlorides. These salts retain moisture and break down the component that surrounds the muscle fibers, resulting in the release of proteins. Polyphosphates are sometimes added to the salts to improve the meat’s juiciness by increased water retention ability, and if added to processed meats, it also increases firmness, emulsion stability, and antimicrobial activity.
Acids. Meats can be made more tender by applying marinades containing acids or alcohol, which break down the outside surface of the meat. The various acids found in marinades include vinegar, wine, and lemon, tomato, or other fruit juices. Not only do marinades tenderize the meat, but they increase flavor and also contribute to color. The maximum benefit of a marinade can be obtained by increasing the surface area of the meat. This may be done by cutting the meat into small pieces, such as teriyaki strips or kabob cubes. Marinades penetrate only the surface of the meat and are therefore not effective at tenderizing large cuts of meat or poultry. Generally, the acid in a marinade is responsible for tenderizing, although some marinades rely on added enzymes from certain tropical fruits such as papayas and pineapples. The meat is then allowed to soak in the marinade, in the refrigerator, from half an hour to overnight, or for several days for sauerbraten.
Mechanical Tenderization. Meat can be tenderized mechanically by a number of methods, including grinding, cubing, needling, and pounding. These actions physically break the muscle cells and connective tissue, making the meat easier to chew. Grinding and cubing meat simply increases the surface-area-to-volume ration, causing the teeth to have less work to do. Needling uses a special piece of equipment to send numerous needle-like blades into the meat, separating the tissues. Because of the equipment required to do this, it is usually not done at the consumer level. Another method of mechanical tenderization, which is more easily done in the home, is simply pounding the meat with a special hammer that breaks apart its surface tissue.
Electrical Stimulation. The meat of beef cattle and sheep, but not swine, becomes more tender when a current of electricity is passed through the carcass after slaughter and before the onset of rigor mortis. Electrical stimulation speeds up rigor mortis by accelerating glycogen breakdown and enzyme activity, which disrupts protein structure, making the meat more tender. In this way, the meat can be immediately cut up without any loss of quality.
