A lot of people wonder about what goes into their sausage while other folks are more curious about what the sausage is actually put into. There is a lot of confusion about sausage casings because there are so many different types and shapes. For example, the type of casings used for hot dogs, bratwurst and summer sausage are completely different from each other.
So, what are sausage casings made from? There are four primary types of casings and they are:
- Natural casings made from animal intestines
- Collagen casings made from beef collagen
- Fibrous casings made from colored filament paper
- Cellulose casings made from viscose
Let’s take a look at each type of casing and how they are used.
The most popular casings for sausages are made from the cleaned intestines of animals, most notably, pigs, sheep and cows. These are called “natural casings” and the most ubiquitous is the 32-34 mm hog casing. This is the casing used for sausages like a bratwurst.
Natural casings come in a wide variety of diameters. Lamb casings are small diameter (19-24 mm) and are used for breakfast link sausage and snack stick type sausages. Beef casings are large diameter (up to 5+ inches) and are typically used for sausages like bologna and salamis
Natural casings are the only casings that form curved links.
Collagen casings are manufactured from beef collagen, are available in multiple diameters and can be either edible or non-edible. Collagen is a protein that is found in connective tissue, tendons etc,
There are advantages and disadvantages of using collagen casings instead of natural casings.
Collagen casings can be used straight out of the bag whereas natural casings have to be detangled and thoroughly rinsed before use. Additionally, natural casings need to be salted and stored in the refrigerator to prevent spoilage whereas collagen casings are a shelf stable product. Collagen casings are also preferred for sausages that must not contain any pork.
The downside to collagen casings is that the links are perfectly straight (some think this is a benefit, I think it is boring) and the links want to unravel. I will often use twine to hold the links in place when I make sausage with collagen casings. I also do not think that collagen casings have as much “pop” when you bite into them.
Fibrous casings were invented in the 1930’s and are made from coated filament paper. These casings are always non-edible and come in clear or mahogany colors.
These casings are larger diameter and usually used as a replacement for natural beef casings. A primary advantage of fibrous casings is that they are extremely strong which lets you really pack the sausage in tight without worrying about blow outs.
Fibrous casings are perfect for large sausages that need a uniform shape and are the casing that I use for Summer Sausage.
Cellulose is a plant based inedible polysaccharide and is the most abundant polymer on earth. Cellulose casings are easy to remove and are designed for large scale and automated manufacturing.
The most common use of cellulose casings is in the production of skinless hot dogs. Here is a great video showing how hot dogs are made using cellulose casings and high speed automation.
Cellulose skins are made by treating cellulose fibers with caustic and other chemicals to make a material known as viscose. The viscose is then transformed into what is called a cellulose casing.