Contact time depends on.... size of meat chunks.... size of grinder plate.... holding temperature while cure etc. is applied to the meat......
http://www.meatsandsausages.com/sausage-making/curing/sausages
The dry method of curing is used to cure meat for sausages. Meat should be cut into smaller pieces, about 2 inches (5-6 cm) and not heavier than 0. 5 lb (250 g). Meat should be thoroughly mixed with salt, Cure #1 (salt, nitrite), sugar (if used) and packed tightly in a container, not higher than 8 inches (20 cm). Going higher increases pressure and slows down curing. Then the meat is covered with a clean cloth and stored in a refrigerator. There are chemical reactions taking place inside meat and the cloth allows the gases to evaporate through. It also prevents the surface of the meat from reacting with oxygen which sometimes creates gray color areas on the surface. This is normal, the meat is fine and there is nothing to worry about. The container does not need to be covered as there are not any unpleasant odors present.
The curing times at 40° F (4° C) (refrigerator temperature) are as follows:
•Meat pieces size 2” - 72 hours.
•Ground meat - 24 - 36 hours, depending on a plate size.
Alternative Curing Methods
Method 1. Grind each meat through a proper plate (as dictated by the recipe). The reason that we grind now and not cut meat into pieces for curing is that salt and sodium nitrite will penetrate a tiny piece of ground meat much faster than a 5 cm (2”) cube. Mix meat with salt and Cure #1. Pack tightly (to remove air) and separately, place each type of ground meat in a container and cover with a cloth to allow breathing. Let it “set” for 3-4 hours at room temperature 20-22°C (68-71°F). Chemical reactions proceed much faster at higher temperatures and so does curing. Add spices, mix all together and stuff casings.
Method 2. Grind each meat through a proper plate (as dictated by the recipe). Mix meat with salt, Cure #1 and other ingredients. Stuff sausages and place in a cooler for 12-24 hours before smoking. When removed from a cooler they have to be conditioned at room temperature for a few hours to remove moisture from the surface.
Method 3. Grind each meat through a proper plate (as dictated by the recipe). Mix meat with salt, Cure #1 and other ingredients. Stuff sausages and hang at room temperature for 2 hours. Transfer to a smokehouse.
When making less than 5 pounds of sausage it is perfectly acceptable to make curing a part of the mixing and conditioning process. This way the sausage is stuffed and ready to go into the smoker and all equipment can be washed and put away. When making large amounts of sausage, you may use a few pork butts or picnics and trimming this meat will take a while. Then you have to grind, mix, stuff and smoke sausages. This operation will take many hours. It is feasible to make sausages on two separate occasions:
1.The first day - meat selection and trimming. The skin and bones are removed, all sinews, gristle and glands are discarded. Meat is cut into small pieces, mixed with salt and nitrite and placed in a refrigerator for 24 hours. Except the knife no equipment was needed.
2.The second day - cured meat goes into the grinder and the sausage making process continues.