Pork casing is the cleaned, processed lining of a pig’s small intestine, used as the outer skin for sausages. It’s one of the most common types of natural sausage casing in the world, responsible for the signature “snap” you get when biting into a bratwurst, Italian sausage, or breakfast link. If you’ve ever eaten a sausage with a thin, slightly chewy skin that bursts when you bite through it, you’ve almost certainly eaten pork casing.
What Pork Casing Actually Is
Natural sausage casings come from the intestines of meat animals, primarily pigs, sheep, and cattle. Pork casings specifically come from the small intestine of the hog. The part that becomes the casing isn’t the full intestinal wall. It’s a specific inner layer called the submucosa, a thin but surprisingly strong sheet of connective tissue. During processing, the other layers of the intestine (the inner mucous lining and the outer muscular wall) are scraped away, leaving just this translucent, flexible membrane.
The submucosa is ideal for sausage making because it’s porous enough to allow smoke and seasoning flavors to penetrate, strong enough to hold ground meat under pressure, and entirely edible. Unlike synthetic or collagen casings, natural pork casings shrink and expand with the meat as it cooks, giving the finished sausage a more natural shape and that characteristic snappy texture.
How Pork Casings Are Processed
At the slaughterhouse, the small intestines are separated from the hog after it passes inspection. The intestines are then flushed with water to remove their contents and mechanically scraped to strip away everything except the submucosa layer. This cleaning process is thorough, often involving multiple rounds of washing and scraping. The result is a pale, semi-transparent tube that looks nothing like an intestine.
Once cleaned, the casings are heavily salted for preservation. Salt draws out moisture and prevents bacterial growth, allowing the casings to be stored and shipped without refrigeration for short periods. In this salted state, they’re bundled into “hanks” (a standard unit of casing length) and packed for sale to sausage makers, butcher shops, and home users. Salted pork casings stored in an airtight container in the refrigerator can last anywhere from 6 to 18 months.
Common Sizes and What They’re Used For
Pork casings are sold by diameter, measured in millimeters. The most common ranges are:
- 29 to 32 mm: The smallest standard hog casing, used for breakfast sausage links and thin fresh sausages.
- 32 to 35 mm: The most popular all-purpose size, commonly used for Italian sausage, bratwurst, and chorizo.
- 35 to 38 mm: A larger diameter suited for Polish sausage, kielbasa, and smoked sausages.
- 38 to 42 mm: The widest standard hog casing, used for large fresh sausages and some specialty links.
Sheep casings are thinner (used for snack sticks and small frankfurters), while beef casings are much larger (used for bologna and salami). Pork casings sit in the middle and cover the widest range of everyday sausage styles, which is why they dominate the market.
How to Prepare Them Before Use
Salted pork casings need to be rehydrated before you can stuff them. The process is simple but takes a little time. Pull out enough casing strands for your batch, then rinse them thoroughly under cool running water to remove as much salt as possible. Next, place the rinsed casings in a bowl of lukewarm water, no hotter than 90°F (32°C), and let them soak for at least one hour. This softens the casing and makes it pliable enough to slide onto a sausage stuffer tube.
After soaking, the casings feel slippery and elastic. You slide one end over the nozzle of your stuffer, bunch the rest of the casing onto the tube like a sleeve, and begin filling. Any leftover casings that you’ve already rinsed should be drained thoroughly, re-salted to cover, placed in a clean airtight container, and stored in the refrigerator for next time.
Safety and Inspection Standards
In the United States, natural casings fall under FDA jurisdiction rather than the USDA’s standard meat inspection system. That means they aren’t required to go through the same HACCP (hazard analysis) framework that applies to cuts of meat. However, facilities can voluntarily request USDA inspection, which allows their casings to bear the official mark of inspection. When they do, inspectors verify that the casings come from animals that passed both pre-slaughter and post-slaughter veterinary examination, and that the casings are “sound, healthful, wholesome, and otherwise fit for human food.”
For imported casings, the exporting country must provide a certificate confirming the same standards: the animals were healthy, inspected, and the casings were prepared under sanitary conditions. In practice, the casings you buy from a reputable butcher supply company or grocery store have gone through extensive cleaning and quality checks before reaching you.
Allergy Considerations
Because pork casings are made from mammalian intestinal tissue, they’re relevant for anyone with alpha-gal syndrome, a meat allergy triggered by tick bites. The CDC lists mammal organ meat, including intestines, as a product that can cause allergic reactions in people with this condition. Gelatin made from pork is also flagged. If you have alpha-gal syndrome, pork casings are something to watch for, and they aren’t always obvious on a label since many sausages simply list “natural casing” without specifying the animal source.
For people following halal or kosher diets, pork casings are not permitted. Some sausage manufacturers use sheep casings, beef casings, or collagen-based alternatives to accommodate these dietary requirements. Collagen casings are manufactured from processed animal hides and tendons, while cellulose casings (which are removed before packaging) are plant-based. These alternatives mimic the function of natural pork casings, though most sausage enthusiasts will tell you the texture isn’t quite the same.
Pork Casing vs. Other Casing Types
Natural pork casings have a few distinct advantages over alternatives. They’re fully edible without any papery or plasticky mouthfeel. They allow airflow during smoking, which means better flavor absorption. And they produce the most satisfying bite, that crisp snap followed by juicy filling that defines a great sausage.
Collagen casings are cheaper and more uniform in size, making them popular for commercial production where consistency matters more than artisan texture. Cellulose casings are used for skinless hot dogs: the sausage is cooked inside the casing, then the casing is peeled off before packaging. Plastic casings, which are not edible, are used for some deli meats like bologna and must be removed before eating.
For home sausage makers and traditional butchers, natural hog casings remain the standard. They’re inexpensive (a single hank can stuff 100 pounds or more of sausage), easy to work with after a quick soak, and they produce results that synthetic options still can’t fully replicate.