This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
All meats shipped from one state to another are under federal surveillance. This includes the meat produced by the larger establishments, about two-thirds of that consumed. Each state and the cities usually have some regulations concerning meats and supervision of local plants.
The purpose of inspection is to insure that the meat sold to the Consumer is from healthy animals, in sound condition at the time of slaughter.
The inspection stamp is round and is placed on each wholesale cut and on all grades of meat. In Fig. 19, the four round stamps are inspection stamps placed on what will be the wholesale cuts of round, rump, sirloin, and short loin.
Inspection of carcasses and the supervision of making of meat products safeguard the consumer. However, in one instance, inspection cannot entirely safeguard the consumer. There is no accurate, quick method that can be used in inspection that detects trichinae in trichinae-infected pork, though federal supervision does insure that products to be consumed without further cooking are so treated that no live trichinae are present. It should be stated that only a small percentage of pork is infected with trichinae.
Trichinosis. Trichinosis is contracted by eating uncooked, trichinae-infected meat, usually pork. Any animal eating pork may contract the disease, however, and cases have been reported in the medical literature that were traced to the eating of raw, jerked bear meat.
It is assumed that anyone buying fresh pork chops, roasts, etc., will cook the meat. But some people grind raw lean pork, season it, and use it in sandwiches. Others in making homemade sausage taste the uncooked product to see that the seasoning is satisfactory.
Ransom and Schwartz found that live trichinae are quickly destroyed by heating the meat to 55°C. They may be destroyed at 50°C. if the meat is held at this temperature for a sufficient time. Ransom found that trichinae are destroyed by freezing, provided the frozen, infected meat is held at a temperature not higher than 5°F. for 10 days.
All lean pork, in plants under federal supervision, used with other meat, or in pork products that are to be consumed without further cooking, must be treated to make sure that any live trichinae that may be present are destroyed. Such products include soft or fresh and dry summer sausages, frankfurters and Vienna-style sausages, Italian and Westphalian-style hams, pork butts in casings, cured pork loins in or without casings, capicola, coppa, cotto salami, and other products.
In general the methods used for destruction of trichinae are (1) freezing and storage and (2) heating, or a combination of one or more of these methods.
The freezing treatment is called refrigeration. The lean pork and pork trimmings are frozen. The specifications, based on the work of Ransom and allowing 10 extra days for a margin of safety, are that the frozen meat must be stored for 20 days at a temperature not higher than 5°F.
Heating is called processing. The specifications, based on the work of Ransom and Schwartz and allowing a margin for safety, are that the meat must be heated to 58.3°C. (137°F.). Some products may be heated to only 128°F. but must be held at this temperature, often in a smoke room, for a specified number of hours.
Salt treatment is used for some products, but a large amount, 4.5 per cent, of salt must be used and a dry cure employed. The meat must be held in this salt cure for a period of 20 to 25 days at specified temperatures and further specific procedures must be followed.