Sausage casings are made from one of four main materials: animal intestines, collagen derived from animal hides, plant-based cellulose, or plastic polymers. The type determines whether you can eat the casing, how it cooks, and whether it works for specific diets. Most sausages you encounter at the grocery store use one of these, and the differences matter more than you might expect.
Natural Casings: Animal Intestines
Natural casings come from the inner lining (submucosa) of intestines from pigs, sheep, or cattle. Sheep casings are the thinnest and most tender, typically used for breakfast links and snack sticks. Hog casings are the standard for bratwurst, Italian sausage, and most fresh sausages you’d throw on a grill. Beef casings are the thickest and strongest, reserved for large sausages like bologna and salami.
These casings are considered the gold standard in sausage production because of their tenderness and high permeability to both moisture and smoke. Their structure consists of wavy collagen fibers in a woven pattern, which gives them elasticity and allows smoky flavor to penetrate the meat during cooking. That satisfying “snap” when you bite into a quality hot dog or bratwurst almost always comes from a natural casing. They’re fully edible and don’t need to be removed before eating.
Collagen Casings: Processed Animal Hide
Collagen casings are manufactured from the protein collagen, most often extracted from cattle hides. The process starts by washing and cutting the hide into small pieces, then using dilute acids or alkalis to break apart the tough molecular bonds holding the collagen together. The collagen is dissolved, purified, precipitated using salt, and then formed into uniform tubes. The entire process happens at low temperatures (around 4°C) to prevent the protein from degrading.
The result is a casing that looks and performs somewhat like a natural casing but can be manufactured to consistent sizes and thicknesses. Most collagen casings are edible, though thicker versions used for salami or summer sausage sometimes are not. They’re popular with commercial producers because they’re easier to work with on high-speed equipment than natural casings, and they cost less. You’ll find them on many store-bought hot dogs and smoked sausages.
Cellulose Casings: Wood Pulp
Cellulose casings are made from plant fiber, primarily wood pulp or cotton. The manufacturing process, known as the viscose method, involves dissolving the pulp in sodium hydroxide, shredding and aging it, then treating it with carbon disulfide to form a compound called cellulose xanthate. This orange-colored material is dissolved again, then extruded into an acid bath that regenerates it into a solid cellulose film shaped as a tube.
Cellulose casings are not edible. They’re used during cooking or smoking to shape the sausage, then peeled off before packaging or before you eat. Skinless hot dogs are the most common example. The manufacturer stuffs the meat into a cellulose casing, cooks or smokes the sausage, then strips the casing away before the product is sealed in its retail package. If you’ve ever wondered why some hot dogs have no visible casing at all, this is why.
Plastic Casings: Synthetic Polymers
Plastic casings are made from polymers like polyamide (nylon), polypropylene, and polyethylene. Many commercial products use multilayer casings that combine several of these polymers, each layer serving a specific purpose. One layer might block oxygen to extend shelf life, while another controls moisture loss. A polypropylene layer oriented in a specific way can reduce oxygen transmission by 45%, which is why these casings dominate the deli meat and lunch meat market.
These casings are never edible. You’ll find them on bologna, some salamis, liverwurst, and other processed deli meats. They’re the thick, shiny wrappers you peel away before slicing. USDA labeling rules require that when artificial casings are left on a product sold in retail containers, the package must carry a prominent statement like “Remove casing before eating” near the product name.
Alginate Casings: Seaweed-Based
A newer option uses alginate, a compound extracted from seaweed. When alginate comes into contact with calcium ions (from calcium chloride, for example), it forms a firm, water-insoluble gel. Sausage makers use a co-extrusion method where the meat filling and the alginate solution are pushed out simultaneously, and the casing sets almost instantly when it hits the calcium solution.
Research has shown that alginate coatings can serve as a suitable alternative to natural casings in fermented sausages. These casings are edible, plant-based, and work for vegetarian, vegan, kosher, and halal products since they contain no animal-derived ingredients. You’ll see them most often on plant-based sausages, though some conventional meat producers use them as well.
How to Tell What’s on Your Sausage
If a sausage has a thin, slightly irregular casing with a natural snap, it’s likely a natural or collagen casing, and you can eat it. If the casing is thick, shiny, and peels away cleanly in a sheet, it’s plastic and needs to come off. Skinless sausages had their cellulose casings removed at the factory.
Colored casings that could give a misleading impression of the meat’s actual color must be labeled “Casing Colored” or “Artificially Colored” near the product name. For natural casings, the source animal matters if you follow dietary restrictions. Pork-based casings are the most common for standard sausages, so if you avoid pork, check the label or buy from a producer that specifies beef or sheep casings. Alginate casings sidestep the issue entirely for anyone avoiding animal products in the casing itself.