Sausage casings are made from one of five main materials: animal intestines, collagen from animal hides, cellulose from wood pulp or cotton, plastic polymers, or plant-based ingredients like seaweed. The type depends on the sausage, and each material behaves differently during cooking, affects texture, and determines whether you can eat the casing or need to peel it off.
Natural Casings: Animal Intestines
The oldest and most traditional option, natural casings come from the intestinal lining of cattle, sheep, or pigs. Specifically, they’re made from the submucosa, a tough inner layer of the intestine that’s stripped of fat and thoroughly cleaned. Sheep casings are the thinnest and most delicate, typically used for breakfast sausages and small links. Hog casings are the go-to for bratwurst, Italian sausage, and Polish kielbasa. Beef casings, the largest, work for bologna and larger salami-style sausages.
Natural casings are fully edible and produce that distinctive “snap” when you bite into a sausage. Testing on frankfurters shows natural casings have noticeably higher tensile resistance than collagen alternatives, meaning they hold up better under pressure and give a firmer bite. They also absorb smoke well, which matters for smoked sausages where flavor penetration is the goal.
By the time natural casings reach a consumer or butcher shop, they’ve been pre-flushed and packed in salt or brine. Before use, they need to be rinsed in cold water three or four times and soaked overnight in the refrigerator. Leftover casings can be repacked in salt and refrigerated for up to a year.
Collagen Casings
Collagen casings are made from the hides of cattle rather than intestines. The cowhide is broken down into a slurry, soaked in acid to swell the collagen fibers, then neutralized with an ammonia solution and extruded into a thin tube shape. The tube is dried with hot air to create a uniform casing.
The result is a casing that looks and performs similarly to a natural one but is far more consistent in size and thickness. That uniformity is why collagen casings dominate commercial sausage production, where thousands of links need to be the same diameter and weight. Most collagen casings are edible, though thicker versions used for dry-cured salami are sometimes peeled before eating. In texture tests on frankfurters, collagen casings fall between the tender bite of a skinless hot dog and the firm snap of a natural casing.
Cellulose Casings
Cellulose casings are made from wood pulp or cotton fibers, processed into a paper-like tube. They are not edible and must be removed before you eat the sausage. This is how most supermarket hot dogs are made: the meat is stuffed into a cellulose casing, cooked, cooled, and then the casing is peeled off by machine before packaging. The result is a “skinless” sausage with a smooth exterior and a softer bite.
Frankfurters made in cellulose casings and then peeled consistently show the lowest bite resistance in texture testing, which is why skinless hot dogs feel tender compared to a natural-casing frank. Fibrous casings, a tougher subtype reinforced with extra plant fiber, are used for larger products like summer sausage and deli meats. These are the casings with printed labels you peel off before slicing.
Plastic and Synthetic Casings
Plastic casings are made from polymers like nylon (polyamide), polypropylene, or polyethylene. Some are multilayered, combining a plastic exterior with a cellulose interior or vice versa. These casings are never edible and always removed before or after cooking.
Their main advantage is impermeability. Plastic casings don’t allow moisture to escape, which keeps the product juicy during cooking and extends shelf life. This makes them ideal for products like bologna, cooked ham, and other deli meats where moisture retention matters more than smoke absorption. Some specialty versions are designed to let liquid smoke pass through one layer while blocking moisture loss through another.
Plant-Based and Vegan Casings
A newer category, plant-based casings skip animal products entirely. The most common material is alginate, a gel derived from seaweed. The sausage filling is extruded through a bath of alginate, which forms a thin gel coating around the outside. This is the method used by Beyond Meat and Impossible Foods for their plant-based sausages.
Another option uses a polysaccharide blend of glycerin, starch, carrageenan (another seaweed derivative), and water. These casings are edible and designed to mimic the texture of a natural casing. Some vegan sausages are cooked in a synthetic casing during production and then sold skinless, so no casing is present in the final product at all.
Which Casings You Can Eat
The quick breakdown:
- Edible: Natural casings (intestine), most collagen casings, and plant-based casings made from alginate or polysaccharides.
- Not edible: Cellulose casings, fibrous casings, and all plastic or nylon casings.
If you’re buying sausages at a grocery store, skinless varieties have already had their inedible casing removed. Sausages sold with a visible casing typically use either natural or collagen casings, both of which are safe to eat. If there’s a thick, papery, or plastic-feeling layer on the outside, peel it off.
Religious and Dietary Considerations
Natural and collagen casings come from animals, which creates a potential issue for people following kosher or halal dietary laws. A beef sausage could be stuffed into a pork-derived casing, for example, with no visible way to tell the difference. The USDA considered requiring species labeling on casings but ultimately left enforcement to private certification. If this matters to you, the most reliable approach is to look for kosher or halal certification on the package, which guarantees the casing matches the dietary requirements. Cellulose, plastic, and plant-based casings avoid the issue entirely since they contain no animal material.