Artificial sausage casings are made from one of three main materials: collagen from animal hides, cellulose from wood pulp, or synthetic plastics like polyamide (nylon) and polyethylene. Which type you’re dealing with depends on the sausage, and whether you can eat the casing depends entirely on the material.
Collagen Casings
Collagen casings are the most common edible artificial casing. They’re made from the corium layer of animal skins, typically from cattle, pigs, chickens, or turkeys. The hides are sourced from government-inspected slaughterhouses, then processed into a gel or paste that gets extruded into a thin, uniform tube.
The manufacturing process works in one of two ways. In the traditional method, collagen is formed into long tubes called “shirred” casings that get loaded onto a stuffing machine, similar to how you’d use natural intestine casings. In the newer co-extrusion method, a continuous stream of collagen paste is applied directly around the meat as it’s being pushed through the machine, forming an endless rope of sausage that gets crimped into individual links. This second method is fully automated and increasingly common in large-scale production.
Collagen from younger cattle (18 to 36 months old) is preferred because it produces a more flexible, workable casing. After the casing is formed, it goes through a crosslinking step that strengthens the collagen proteins and makes the tube hold its shape during cooking. You’ll find collagen casings on breakfast sausage links, snack sticks, and many fresh sausages at the grocery store. They’re edible and don’t need to be removed before eating.
Cellulose Casings
Cellulose casings are made from tree pulp. The wood fiber is dissolved and reformed into a thin, transparent tube. These casings are not edible and must be removed before eating.
If you’ve ever bought skinless hot dogs or frankfurters, you’ve encountered cellulose casings. The sausage is cooked and smoked inside the cellulose tube, which gives the exterior its familiar snap and shape. Then the casing is peeled off by machine before the product is packaged. The cellulose acts as a mold during processing rather than a permanent wrapper. Because the source material is plant-based, cellulose casings contain no animal products, though the sausage inside them obviously might.
Plastic and Fibrous Casings
Plastic casings are made from synthetic polymers, most commonly polyamide (nylon), polyethylene, or polyvinylidene chloride. These are the thick, tough casings you’ll find on summer sausage, bologna, and deli meats. They are never edible.
Some plastic casings are engineered to shrink tightly around the meat when heated, giving the finished product a smooth, uniform appearance. Others are designed as high-barrier packaging that blocks oxygen and moisture to extend shelf life. The specific polymer blend determines how the casing performs: a basic polyamide casing offers moderate barrier properties, while more advanced formulations mix polyamide with small amounts of water-attracting compounds to allow controlled levels of smoke and moisture to pass through during processing.
Fibrous casings are a hybrid. They start with a paper or fabric core that’s coated or impregnated with a material (often cellulose or plastic) to create a strong, rigid tube. These are used for large-diameter sausages like salami and liverwurst, where the casing needs to hold a heavy fill without stretching or breaking. Like plastic casings, fibrous casings must be peeled off before you eat the sausage. Any product sold with an inedible casing still on must carry a label statement like “remove casing before eating.”
How Casing Material Affects Flavor
The material isn’t just structural. It directly influences how the sausage tastes and feels. Different casings allow different amounts of smoke and moisture to pass through, which changes the final product significantly.
Collagen casings behave a lot like natural intestine casings in this regard. When first exposed to heat, the collagen dries out and becomes less permeable to moisture. This initial drying phase is actually important because it sets up the right conditions for smoke to penetrate the surface evenly. Once the desired level of smoke flavor and color is reached, continued drying seals the casing further, locking moisture inside the sausage. This is why collagen-cased sausages can develop a rich, smoky exterior while staying juicy inside.
Plastic casings, by contrast, are generally poor at letting smoke through. Some advanced polyamide blends have been specifically engineered to allow smoke compounds (particularly phenol, one of the key flavor molecules in wood smoke) to penetrate at rates close to what collagen casings achieve, around 110 to 160 grams per square meter per day at cooking temperatures. But standard plastic casings block smoke almost entirely, which is why some processed meats rely on liquid smoke injected into the meat itself rather than traditional smoking.
Plant-Based and Vegan Casings
A newer category of artificial casing uses alginate, a gel-forming compound extracted from seaweed. In this process, an alginate paste is co-extruded onto the surface of the sausage as it’s being stuffed, then treated with a calcium solution that causes the paste to firm up into a solid casing. The reaction happens at room temperature, no heating required.
Alginate casings are fully vegan, which makes them the go-to option for plant-based sausages. They also work well for conventional meat sausages where manufacturers want to avoid animal-derived collagen for cost or dietary reasons. The texture is softer than collagen, closer to a thin gel than a traditional snap casing, but it holds together well enough for grilling and pan-frying.
How to Tell What’s on Your Sausage
If the casing is thin, slightly translucent, and you can bite through it easily, it’s likely collagen or natural intestine. If the sausage has no visible casing at all (like a standard hot dog), it was probably processed in cellulose that was removed before packaging. If the casing is thick, plastic-feeling, or has printing on it, it’s a synthetic plastic or fibrous casing and needs to come off.
Packaging labels are your most reliable guide. Products with inedible casings left on are required by USDA rules to include a prominent removal instruction near the product name. Collagen casings, since they’re edible, won’t carry that warning. When in doubt, if you can’t easily chew through the casing, peel it off.