Sausage casings are made from one of five main materials: animal intestines, collagen from animal hides, cellulose from wood pulp, food-grade plastics, or seaweed-derived alginate. Which one you’re eating (or peeling off) depends on the type of sausage. Natural intestine casings remain the standard for traditional sausages, but manufactured alternatives now dominate high-volume commercial production.
Natural Casings: Animal Intestines
The oldest and most traditional casings come from the digestive tracts of pigs, cattle, and sheep. Despite what you might assume, the finished casing isn’t the whole intestinal wall. During processing, the intestines are stripped of their contents, flushed, and then passed through rollers that scrape away most of the tissue layers. What’s left is primarily the submucosa, a thin layer rich in collagen fibers that gives the casing its strength and flexibility.
Each animal produces casings suited to different sausage styles, largely because of diameter:
- Sheep casings are the narrowest, typically 20 to 30 mm across. They’re used for slim sausages like hot dogs, breakfast links, chipolatas, and merguez. Sheep casings are prized for their distinctive “snap” when you bite through them.
- Hog casings range from about 30 to 45 mm and produce the fatter sausages most people picture: bratwurst, Italian sausage, kielbasa, and andouille.
- Beef casings are the largest. Processors use cattle small intestines, large intestines, and even the esophagus and bladder for different products, from ring bologna to large salamis.
Only the small intestines of sheep are used for casings. Pigs and cattle, by contrast, contribute multiple parts of their digestive tract. Pig large intestines (called “middles” and “caps” in the trade) are used for larger sausages like liverwurst, while the terminal end of the large intestine, known as the “bung,” works for wide specialty products.
Natural casings are entirely edible and don’t need to be removed before eating. They’re also permeable to smoke and moisture, which is why traditionally smoked sausages almost always use them. That permeability lets smoke flavor penetrate the meat and allows dry-cured sausages like salami to lose moisture at a controlled rate during aging.
Collagen Casings
Collagen casings are manufactured from the inner layer of cattle hides. The collagen is extracted, processed into a gel, and then extruded into uniform tubes. The result looks and performs similarly to a natural casing but with more consistent sizing, which matters for large-scale production where every sausage needs to weigh the same.
Most collagen casings are edible, though thicker versions made for dry-cured or large-diameter sausages sometimes aren’t. Edible collagen casings are common on breakfast sausage links and snack sticks. Their bite and texture are strongly influenced by how the sausage is dried and smoked during production. Getting the humidity right during cooking is critical to producing that satisfying snap rather than a tough, chewy skin.
Because collagen casings come from animal products, they aren’t suitable for vegetarian or vegan sausages. They are, however, widely accepted for halal and kosher products when sourced from approved animals.
Cellulose Casings
Cellulose casings are made from wood pulp, specifically from regenerated cellulose derived from plant fibers. They’re one of the most popular artificial casings in the meat industry and are used primarily for hot dogs and skinless sausages.
Here’s the key distinction: cellulose casings are not eaten. The sausage is stuffed into the cellulose tube, cooked or smoked, and then the casing is mechanically peeled off before packaging. That’s why some hot dogs appear to have no casing at all. The cellulose serves as a mold during cooking, giving the sausage its shape and allowing smoke to pass through (cellulose is permeable), but it’s removed before the product reaches you. If you’ve ever bought “skinless” franks, they were made with cellulose casings.
Plastic and Synthetic Casings
Plastic casings are made from food-grade polymers, most commonly polyamide (nylon), polypropylene, polyethylene, or multi-layer combinations of these materials. They’re engineered as barrier casings, meaning they block moisture loss and oxygen exposure. This makes them ideal for cooked deli meats, bologna, and large-diameter emulsion sausages where you want the product to retain moisture rather than dry out.
Plastic casings are never edible. Products sold in retail packaging with the casing still on must carry a label stating “Remove casing before eating,” per USDA requirements. You’ll recognize these casings on summer sausage logs, bologna, and some smoked sausages as the thick, sometimes printed outer layer you peel away.
Multi-layer casings represent the more engineered end of the spectrum. These combine different polymers to achieve specific properties: an outer layer that resists moisture loss, an inner layer that allows smoke to penetrate, or printed surfaces for branding directly on the casing.
Plant-Based and Alginate Casings
The newest category uses alginate, a substance extracted from the cell walls of brown seaweed. Alginate is a natural polysaccharide that forms a firm gel when it comes in contact with calcium, and manufacturers use this reaction to create edible casings through a process called co-extrusion. The sausage filling and the alginate coating are applied simultaneously, with the casing forming around the meat (or plant-based filling) in a single step.
Alginate casings are edible, plant-derived, and compatible with vegetarian, vegan, halal, and kosher dietary requirements. They’re increasingly used for both traditional meat sausages and plant-based alternatives. Some producers add ingredients like pea protein or emulsifiers to the alginate coating to fine-tune its texture and performance during drying or cooking. Research on dry-fermented sausages like Spanish fuet has shown alginate coatings can perform comparably to collagen casings for certain products.
How Casing Choice Affects Texture and Flavor
The casing isn’t just a container. It directly shapes the eating experience. Natural sheep gut casings deliver the strongest “snap” or “knack” when you bite into a sausage. That crisp pop followed by the rush of juice is largely a function of the casing, not just the meat inside. Collagen casings can approximate this snap, but achieving it requires precise control of humidity, smoking temperature, and drying time during production.
Permeability is the other major variable. Natural and cellulose casings allow smoke and moisture to pass through freely, which is essential for smoked and dry-cured sausages. A dry salami needs to lose moisture slowly and evenly over weeks, and only a permeable casing allows that. Plastic casings do the opposite, locking moisture in, which is why bologna stays soft and moist rather than developing a firm, dried texture.
For fresh sausages that you’ll cook at home on a grill or in a pan, the casing needs to perform under direct heat without splitting or becoming tough. Natural hog casings and thin collagen casings handle this well. Thicker synthetic casings would be a poor fit for a fresh bratwurst but work perfectly for a summer sausage that’s cooked once at the factory and then sliced cold.