USDA Rules can be found here: https://www.law.cornell.edu/cfr/text/9/318.10
Above Edit By Bob K
In 2003, Dr. M. Ellin Doyle at the University of Wisconsin in Madison wrote that trichinella spiralis is so resistant to salt that it takes 8 to 9 percent to kill the larva. Levels above about 4 per cent are not palatable to humans. Many dry-cured (raw) sausages are prepared with salt levels nearing 3-1/2 per cent because the higher salt volume controls pathogenic bacteria by "binding" the water (Aw) until the lactic acid bacteria has had a chance to work by competing with the pathogenic bacteria for sugar.
A couple of years ago, a new member wrote in and asked:
Absolutely we freeze pork to kill any possible trichinae. But simple freezing will not destroy the microorganism. We must "Deep" Freeze meat - BELOW ZERO! Although the FSIS has done much to eradicate the disease by enforcing modified laws, especially after the mid 1970`s, there yet remain about 40 cases of trichinosis each year in the U.S. alone. Most of these cases stem from smaller farms yet feeding their stock the entrails of previously slaughtered pork and because it has not yet been completely alleviated and we must never take a chance or take it for granted that it couldn`t yet possibly affect our sausage making.Do you guys freeze your pork to kill any possible trichinae before making salami or just take a chance and not worry about it?
In North America, there are five known species of Trichinella. They are Trichinella spiralis, T. nativa, T. pseudospiralis, Trichinella T-5, and Trichinella T-6. The one we deal with most often in pork is trichinella spiralis. The other four occur mostly in game animals. Species T-5 is found mostly in bears and other wildlife in the eastern United States, while species T-6 is mostly in bears and other wildlife in the Northwestern United States. Species T. nativa is found in Alaska. Both T. nativa and Trichinella T-6 are resistant to freezing. Trichinella pseudospiralis has been reported infrequently from birds, but can infect pigs also.
You would be surprised at just how many people believe that simple freezing will destroy trichinella spiralis. Actually, the majority of people believe it, and that frightens me. I often think of the folks who shoot javelinas and think simply freezing the carcass will take care of trichinella spiralis. It absolutely will not! In fact, The Division of Infectious Disease, Department of Medicine, at Massachusetts General Hospital has concluded that "Smoking, salting, or drying meat are not reliable methods of killing the organism that causes this infection". Further, "Only freezing at subzero temperatures (Fahrenheit) for 3 to 4 weeks will kill the organism". If folks ever gazed into a microscope and saw the round nematode worm embedded far into human muscle tissue, they would surely think twice about proper sub-zero temperatures. The first time I saw the living microorganism beneath the microscope, I thought I'd lose my lunch! The thing that alarms me is that most people do not have the means of freezing meat at these cryogenic temperatures - so, they take the chance. Yet, if the pork has come from a reliable grocer rather than an "independent small farmer", you will be pretty much safe.
'Wanna get' really scared? Here's how the little buggers work: Trichinella cysts break open in the intestines and grow into adult roundworms whenever a person eats meat from an infected animal. These roundworms produce other worms that move through the stomach wall and into the bloodstream. From here, the organisms tend to invade muscle tissues, including the heart and diaphragm, lungs and brain. At this point, trichinosis becomes most painful.
But we can get rid of it right? Wrong! The medications Mebendazole or albendazole may be used to treat infections in the intestines, but once the larvae have invaded the muscles, there is no specific treatment for trichinosis and the cysts remain viable for years. Complications of the disease include encephalitis, heart arrhythmias, myocarditis, (inflammation), and complete heart failure. Pneumonia is also a common complication. So, what do we do? Purchase pork from a known, reliable, suppliers who conform to USDA and FSIS rules and imports commercially-grown pork. Or, you can cryogenically treat your own if you are a small producer of hogs and insist on feeding your piggies the entrails of other animals.
Employing FSIS rules, hog producers have come so far since the mid 1970's that trichinella spiralis isn't much of a threat any longer in commercial pork. However, about 40 people a year are still infected by pork that has been "home grown" by local hog raisers who will not comply. When the animal's feed is infected, the cycle starts all over again. One of these days, small producers will "get it" and adhere to modern feeding practices recommended by the USDA.
For your reference, here are the rules of the United States Department Of Agriculture - Meat Inspection Division for destroying trichinae:
The Meat Inspection Division of the United States Department Of Agriculture arranges the size, volume, and weight of meat products into "groups" to specify handling instructions.
Group 1 "comprises meat products not exceeding 6" (inches) in thickness, or arranged on separate racks with the layers not exceeding 6" in depth, or stored in crates or boxes not exceeding 6" in depth, or stored as solidly frozen blocks not exceeding 6" in thickness".
Group 2 "comprises products in pieces, layers, or within containers, the thickness of which exceeds 6" but not 27" and products in containers including tierces, barrels, kegs, and cartons, having a thickness not exceeding 27". The product undergoing such refrigeration or the containers thereof shall be spaced while in the freezer to insure a free circulation of air between the pieces of meat, layers, blocks, boxes, barrels, and tierces, in order that the temperature of the meat throughout will be promptly reduced to not higher than 5 degrees F., -10 degrees F., or -20 degrees F., as the case may be".
Item 1: Heating & Cooking
"All parts of the pork muscle tissue shall be heated to a temperature of not less than 138° F." Whenever cooking a product in water, the entire product must be submerged for the heat to distribute entirely throughout the meat. Always test the largest pieces since it always takes longer to reach the 138°F temperature in thicker pieces. Always test the temperature in a number of places.
Item 2: Refrigerating & Freezing
"At any stage of preparation and after preparatory chilling to a temperature of not above 40° F., or preparatory freezing, all parts of the muscle tissue of pork or product containing such tissue shall be subjected continuously to a temperature not higher than one of these specified in Table 1, the duration of such refrigeration at the specified temperature being dependent on the thickness of the meat or inside dimensions of the container."
Table 1: Required Period Of Freezing At Temperature Indicated
Temperature Group 1 (first number of days) Group 2 (second number of days)
+05° F. 20 days / 30 days
-10° F. 10 days / 20 days
-20° F. 6 days / 12 days
Item 3: Curing Sausage
"Sausage may be stuffed in animal casings, hydrocellulose casings, or cloth bags. During any stage of treating the sausage for the destruction of live trichinae, these coverings shall not be coated with paraffin or like substance, nor shall any sausage be washed during any prescribed period of drying. In preparation of sausage, one of the following methods may be used:
Method No. 1:
"The meat shall be ground or chopped into pieces not exceeding 3/4" in diameter. A dry-curing mixture containing not less than 3-1/3 lbs. of salt to each hundredweight of the unstuffed sausage shall be thoroughly mixed with the ground or chopped meat. After being stuffed, sausage having a diameter not exceeding 3-1/2" measured at the time of stuffing, shall be held in a drying room not less than 20 days at a temperature not lower than 45 degrees F., except that in sausage of the variety known as pepperoni; if in casing and not exceeding 1-3/8" in diameter at the time of stuffing, the period of drying may be reduced to 15 days. In no case, however, shall the sausage be released from the drying room in less than 25 days from the time the curing materials are added, except that the sausage of the variety known as pepperoni, if in casings not exceeding the size specified, may be released at the expiration of 20 days from the time the curing materials are added. Sausage in casings exceeding 3-1/2" but not exceeding 4" in diameter at the time of stuffing shall be held in a drying room not less than 35 days at a temperature not lower than 45 degrees F., and in no case shall the sausage be released from the drying room in less than 40 days from the time the curing materials are added to the meat.
Method No. 2:
"The meat shall be ground or chopped into pieces not exceeding 3/4" in diameter. A dry-curing mixture containing no less than 3-1/3 lbs. of salt to each hundredweight of the unstuffed sausage shall be thoroughly mixed with the ground or chopped meat. After being stuffed, the sausage having a diameter not exceeding 3-1/2" measured at the time of stuffing, shall be smoked not less than 40 hours at a temperature of not lower than 80 degrees F. and finally held in a drying room not less than 10 days at a temperature not lower than 45 degrees F. In no case, however, shall the sausage be released from the drying room in fewer than 18 days from the time the curing materials are added to the meat. Sausage exceeding 3-1/2", but not exceeding 4" in diameter at the time of stuffing, shall be held in a drying room following the smoking as above indicated, not less than 25 days at a termperature not lower than 45 degrees F., and in no case shall the sausage be released from the drying room in less than 33 days from the time the curing materials are added to the meat.