Frankfurters are good examples of fine-cut sausage that is produced and stuffed into small casings.
Grinding is the first operation in manufacturing frankfurters, and these procedures vary. Some sausage makers grind the beef trimmings in the frankfurter meat formula through a three-eighth-inch plate and depend upon the cutter to give the meat the necessary fineness before it is stuffed. Other sausage makers prefer to grind the meat through a one-eighth-inch plate.
The first procedure increases the capacity of the grinder and does not heat the meat as much, but the latter is said to give better extraction of soluble protein, leading to better grinding qualities. Usually, lean meats are ground or chopped to a finer consistency than fat meats.
Chopping
After the lean meats have been ground, they are placed in the cutter with salt and curing ingredients, and chopped at 42 degrees to 45 degrees F. Enough moisture should be added at this point to produce a brine concentration (salt dissolved in the moisture of lean meat plus added moisture) of 7 percent to 8 percent, ensuring maximum extraction of salt soluble contractile proteins.
At this point, fat meats, spice, remaining water and other ingredients are added, and the chopping procedure is ended at a temperature of 62 degrees to 63 degrees F. Temperature, rather than time, is a better guide in chopping.
If an emulsion mill is to be used after chopping, the temperature in the chopper generally is held in the range of 52 degrees to 55 degrees F before going into the emulsion mill.
The other ingredients, particularly non-meat proteins such as cereal flours and milk powder, are added with the last ingredients since they readily absorb water and may make it less available for soluble protein extraction.
In cases where "hard" fats, such as beef or mutton are used, the temperatures for making the fat plastic enough to produce a good emulsion should be 2 degrees to 3 degrees F higher in the last two steps.
Non-skeletal meat and any meat portions high in collagen should be treated as part of the fat meat portion.
Blending
Where blenders are used prior to the chopper or emulsion mill, the procedure is somewhat the same as previously described. The lean meat is ground (one-eighth-inch particles) and loaded in the blender with salt, cure, spice and sufficient water to produce a 7.5 percent brine concentration. The meat is blended to 42 degrees to 45 degrees F. The ground fat meat portion (usually one-eighth- to three-eighth-inch particles) and other ingredients should be added and blended to 50 degrees to 55 degrees F.
A sample may then be taken of the mixture to determine fat and moisture levels, and adjustments may be made if necessary. The meat mixture is then unloaded and chopped or emulsified to a final temperature of 60 degrees to 70 degrees F.
Since blenders do not act to raise temperature, hot water is often used during blending. Water as high as 180 degrees F is often used with frozen or partially-frozen meat. If water of this temperature is used, it could cook the protein and ruin its binding ability. In this case, the water should be sprayed through a single discharge pipe. The use of more than 50 percent frozen meat may preclude reaching the optimum protein extraction temperature even if hot water is used.
The air incorporated into the emulsion must be removed in order to achieve uniformity and desirable internal appearance and texture. Most continuous stuffers are equipped with vacuumizing capabilities.
It is also possible to use a vacuum chopper or a vacuum mixer or blender. The chopped meat is next placed in the stuffer. Cellulose, collagen and sometimes sheep and hog casings are used for frankfurters.
Cellulose casings come in cardboard holders ready for transferring diectly to the stuffing horn or loading device of the stuffer and are stuffed and linked while dry. Collagen casings are stuffed dry, but depending on the equipment may be moistened while passing through the linking equipment.
Salted hog and sheep casings are flushed with water prior to being placed upon the stuffing horn. All of this water is expelled from the casing by stripping between the fingers before it is stuffed. As the casing fills with meat, it is allowed to work off the stuffing horn. It is held firmly between the fingers of the operator to insure that it is filled to maximum capacity and to eliminate air pockets.
Linking machines automatically link sausage in measured lengths. The selection of a machine should be based on possible labor savings, ease of adjustment of machine from one length link to another, possible damage to casings, initial expense and cost of upkeep. Most frankfurters and simialr products are stuffed and linked with equipment that is specially designed for that purpose and with capacities of up to 3,000 pounds per hour.
After stuffing, the sausage moves to the smokehouse (or continuous processor) where smoking and cooking take place.
Chilling
Next is chilling. Frankfurters must be handled carefully during and after chilling. The sausage is chilled after cooking to an internal temperature of 85 degrees F. by spraying with cold water. This plumps the sausage. It is next surface-dried and then transported to a cooler while still loaded on its sticks. If the right amount of cold water is used on the sausage, the heat in the center of the sausage helps to dry the outside surface. A momentary spraying with very hot water produces the same result.
The sausage cooler must by dry and sanitary and have a good circulation of air. Stagnant air or excessive humidity encourages mold and spoilage. Condensation drip from pipes or ceilings in sausage storage rooms is especially dangerous. However, the drying action, caused by the circulation of air, must not be carried to the extent of excessive removal of the moisture, which is a part of the product. If this happens, the quality, yields and peelability will suffer, and the sausage will have a shrunken and unsightly appearance.