Frozen meat and poultry are obtainable in retail markets in larger cities. In addition many people freeze meat in mechanical freezer units, and the practise of obtaining compartments and freezing fresh meat in local cold storage plants in rural and small urban communities is increasing tremendously. Hence, the cooking of frozen meat attains importance and knowledge of what happens to the meat during freezing gives understanding of why it should be cooked soon after defrosting, if it is defrosted before cooking.

Freezing. When meat is frozen, the unbound water forms ice crystals. These crystals on thawing, with their dissolved substances tend to exude from the cut surfaces of the meat. Empey found the drip from frozen and thawed meat very similar in composition to fluid pressed from unfrozen meat. He found a direct relationship between the hydrogen-ion concentration and the capacity of the muscle to hold fluid. Minimum drip occurred when the pH of the muscles had not dropped below 6.3. However, he did no work to determine the tenderness of the meat in connection with pH or at what pH it would be most desirable to freeze the meat for quality and palatability after cooking. The writer's experience thus far is that meat that is not tender before freezing does not improve in tenderness by freezing. This would indicate that for palatable meat it is preferable for meat to be ripened sufficiently before freezing.

Meat may be frozen rapidly or slowly. In rapid freezing the meat is subjected to a very low temperature so that freezing occurs in a short time. The advantage of this method is supposed to be due to the fact that the ice crystals have little time to grow; hence they are smaller and break the fibers to a smaller extent. There is considerable controversy as to which is the best procedure. Moran says that in their studies rapid freezing possessed no advantages over slow freezing as regarded the quality of the product, but that in each case the most important factor affecting the quality was the storage temperature. Lowe and Keltner found no difference in the quality of poultry frozen by rapid and slow methods. Many reports in the literature indicate that it is preferable to keep the meat or poultry at quite low temperatures, - 10° to - 15°F., to prevent desiccation of the meat. Tressler believes it is desirable to have the temperature as uniform as possible, for a fluctuating temperature also increases moisture loss. Each piece of meat or bird should be wrapped to prevent moisture loss. Tressler says, "Severe desiccation causes a considerable loss of flavoring components, and makes the frozen product tougher, less easily cooked, and therefore, less desirable for food."

Defrosting. The method of defrosting seems to be particularly important for poultry. Snyder found poultry defrosted in water markedly less desirable in flavor than poultry defrosted in cold air, i.e., in a refrigerator.

The method of defrosting was also more important than drawing and length of storage period in determining flavor, although the giblets of undrawn birds were not so desirable as those of drawn birds.

Many questions are received from Iowa women regarding the flavor of poultry frozen and stored in local plants. It is a common practise for these women to defrost the poultry in water, but their frozen meat is defrosted in cold air.

Beef and meats having extensive cut surfaces of the muscles tend to "drip" more than poultry after defrosting. Since loss of this fluid also results in loss of flavor and nutritive value, it is desirable to cook the meat soon after defrosting or even before defrosting. Defrosted meat is also more susceptible to bacterial attack.

Fig. 23. - Standing rib roast of beef. Showing thermometer inserted for reading interior temperature of the meat.

Cooking. Defrosted meat is cooked in the same way as unfrozen meat. But if cooking is started before the meat is defrosted, then the temperature and time of cooking need to be changed to allow the meat both to thaw and to cook. Otherwise, a steak or roast can be served with a brown appetizing exterior and still be frozen in the interior. The writer prefers to start cooking all frozen steaks and chops before defrosting, as there is then no loss of fluid and flavor. But the meat is not seared. The cooking temperature must be low and the cooking time increased to at least 3 or 4 times longer than for unfrozen meat. Because of the longer time required for thawing and cooking the exterior browns sufficiently without searing.

The use of salt. There is no advantage in salting large pieces of meat, as the salt is placed on the surface of the meat and does not penetrate to any appreciable extent during cooking. Part of the salt is carried from the surface of the meat by the juices and into the drippings. Snyder determined the total and nitrogenous losses in beef roasts and stews. The meat was all from the same carcass, the cooking conditions were standardized, and the roasts or stews cooked in pairs. Similar cuts, cut as nearly alike as possible by an experienced meat cutter, from the right and left side of the animal, were used for each pair, one of the pair being salted, the other left unsalted. The quantity of salt used was about the amount that would be used by housewives in cooking meat, 1.5 grams per pound of meat. The losses were determined on the basis of the uncooked weight of the meat and on surface area, but both methods showed no appreciable differences in the total or nitrogenous losses of the salted and unsalted meats. In the salted roasts the flavor penetrated to less than 1/2 inch in depth. The layer in which the salt had penetrated was a deeper gray in color than the corresponding layer on the unsalted roast.

Records for cooked meats. In addition to the records of weight, time of cooking, etc., a tracing may be made of the cut surface of roasts, steaks, and chops. A piece of parchment paper is laid over the cut surface and the entire surface rubbed lightly with the fingers to bring it in contact with the meat. The fat leaves the paper semi-transparent, and the moisture from the lean portion slightly puckers the paper. A pencil tracing is made around the edge of the meat and the fat and bone layers. A tracing of this sort is better than a photograph in that the dimensions are actual size. It also shows the exact distribution of fat, lean, and bone. A good grade of thin typewriter paper can be used for making these prints.