Yes, traditional sausage casings are made from animal intestines. Specifically, they come from a layer called the submucosa, a thin, tough tissue found inside the intestinal walls of pigs, sheep, and cattle. This has been the standard method for making sausages for thousands of years, and natural intestine casings remain widely used today alongside several synthetic alternatives.
What Part of the Intestine Becomes the Casing
A raw intestine is a multilayered tube, but sausage casings don’t use the whole thing. Processors strip away the inner lining (the mucosa) and the outer muscular layers, leaving behind the submucosa. This middle layer is mostly collagen, which gives it the right combination of strength, flexibility, and permeability. It’s thin enough to bite through easily but strong enough to hold its shape during cooking.
Each animal produces casings with different characteristics. Sheep intestines yield the thinnest, most delicate casings, commonly used for breakfast sausages and merguez. Hog casings are slightly thicker and suit bratwurst, Italian sausage, and most standard link sausages. Beef casings are the largest and most robust, reserved for bigger products like salami and bologna.
How Intestines Become Food-Safe Casings
Fresh intestines go through extensive cleaning before they’re sold. At processing facilities, the intestines are flushed, mechanically scraped to remove the unwanted tissue layers, and then washed repeatedly. After cleaning, they’re packed in salt, which preserves them and prevents bacterial growth. Salted casings can last for months when refrigerated.
Before use, the casings need to be rinsed thoroughly to remove the salt, then soaked in water no hotter than 90°F for at least an hour. This rehydrates them and makes them pliable enough to slide onto a stuffing tube. Any leftover casings after a sausage-making session can be drained, re-salted, and stored in an airtight container for later use.
How to Tell Natural From Synthetic Casings
Natural casings have a slightly irregular appearance. They vary a bit in diameter along the length of the sausage, and the surface has a subtle, organic texture rather than a perfectly uniform look. When you bite into a sausage with a natural casing, there’s a distinctive snap, a clean pop that gives way to the filling inside. This texture is one of the main reasons many sausage makers still prefer them.
Synthetic casings, by contrast, tend to look more uniform and consistent. Some are edible, some are not, and the distinction matters:
- Collagen casings are the closest synthetic alternative to natural casings. They’re made from the collagen in cattle hides rather than intestines, and most varieties are edible. They come in both thin (edible) and thick (non-edible) forms.
- Cellulose casings are made from processed wood pulp or cotton fibers. They allow smoke to penetrate during cooking but are peeled off before the sausage is sold. Skinless hot dogs are the classic example.
- Plastic casings are completely impermeable and never edible. They’re used for products like braunschweiger and certain deli meats, and they must be removed before eating.
If a sausage at the grocery store has a casing you can eat, it’s either a natural intestine casing or a thin collagen casing. If the package says “skinless” or the sausage has no visible casing at all, the casing was removed during manufacturing.
Natural vs. Collagen Casings: Performance Differences
Natural casings hold more water and are more permeable to moisture and smoke, which affects how the sausage cooks and how much weight it retains. A study published in the Journal of the Science of Food and Agriculture compared sheep casings to collagen casings and found that natural casings had higher water content, greater swelling capacity, and more water vapor permeability. Interestingly, though, taste testers in that study didn’t consistently rate natural-cased sausages higher than collagen-cased ones.
For home cooks and small-batch sausage makers, natural casings are still the default choice. They’re forgiving during stuffing, they stretch and contract with the filling, and they perform well on the grill, in the oven, and in the smoker. Collagen casings are more popular in commercial production because they’re uniform in size and don’t require the soaking and handling that natural casings demand.
Religious and Dietary Considerations
The animal source of a natural casing matters for anyone following halal or kosher dietary laws. Hog casings, the most common type in European and American sausage-making, are prohibited under both traditions. Sheep and beef casings are acceptable alternatives, provided the animal was slaughtered according to the required religious rites and the casing can be traced back to that certified source.
For vegetarians and vegans, natural casings are obviously off the table, and collagen casings are also animal-derived. Cellulose casings are plant-based but are removed before eating, so they don’t end up in the final product. Many plant-based sausage recipes skip casings entirely, shaping the filling by hand or wrapping it in foil or parchment during cooking to hold its form.
How Casings Are Regulated in the U.S.
Natural casings occupy an unusual spot in the U.S. food safety system. They fall under the jurisdiction of the FDA rather than the USDA’s Food Safety and Inspection Service, which handles most meat products. This means casings are not required to go through the USDA’s mandatory inspection process or carry the USDA mark of inspection, though facilities can voluntarily request that inspection, particularly when casings are destined for export. Imported casings are also regulated by the FDA, not the USDA. When casings are presented for export certification, inspectors verify that they are sound, wholesome, and fit for human consumption.