What Is Sausage Casing Made of?

An Introduction to the Material, Manufacturing Processes, and Their Quality Markers.

When people ask what sausage casings are made of, they're usually looking for a simple answer.

But the real answer depends on many factors such as the type of casing, how it was harvested, then processed and/or treated prior to distribution to suppliers, and the storage and care by the retailer.

• Some casings come directly from animal anatomy, such as small intestines (aka "Runners" or "Rounds"), large intestines ("Middles" and "Bung").
• Some are made from purified bovine collagen.
• Some are made from plant fibers.
• Others are synthetic polymer films designed for industrial processing.

Understanding what each casing is made of — and how it's processed — explains why it behaves the way it does during stuffing, smoking, drying, slicing, and eating.

This guide focuses on the material origin and manufacturing of sausage casings, not buying advice. If you’re looking for guidance on selecting the right casing for your specific recipe, we break that down in detail in our guide on where to buy sausage casings. Here, we're going a little deeper.

What Are Natural Casings: The Submucosa Layer of the Intestinal System

Natural casings are made from the submucosa layer of the small intestine of mammals. The Submucosa is the collagen-rich, fibrous, and vascular tube-layer of the small intestines between the muscular layer ("Muscularis") on the outside and the Mucosa on the inside. Interestingly, the Mucosa is composed of two parts (crypts and villi), which are like millions of peaks and valleys on a very small scale, which move digested food along while still extracting nutrients through the walls. If you splay out your fingers... the crypt is the 'webbing' and the fingers and tips are called the villus/villi. The health and structural strength of this tube-layer will determine how well your sausage can withstand stuffing without breaking, how many/size of veins structures are visible, and the color of the casing.

Quality in, Quality out:

When the submucosa is healthy and processed carefully, this will give the 'casings' the greatest durability for stretch (bending) and tensile strength during stuffing. This is where Grading gets quite important. An animal with a B grade or lower intestines generally had poor-quality feed, while a higher-quality diet will ensure a denser, more collagen-rich structure. The Sausage Maker's natural casings are only A/AA or A/B, depending on the grading system used, which means they are used most often for commercial high-speed stuffers (hydraulic) and discerning home sausage makers. Providing animals with good-quality feed is one part of the quality equation.

Cleaning and Processing of Natural Casings:

Once the animal has been harvested, the casings are removed of their contents, drained, and cleaned thoroughly, with multiple passes with water, and the inner mucosa layer (from earlier) is essentially scraped away, leaving just the submucosal layer for sausage casing use. The removal process uses sharp-tooled machines or is performed manually with specialized knives. If the animal feed was good and the pulling/scraping of the mucosa was done with care... the final result is a white, thin, translucent yet durable, visually appealing casing that will allow the meat mix inside to shine through. It also allows the smoke to develop a beautifully vibrant color, with the smoke flavor permeating and finally ending with a *snap* with each bite! Finally, the casings are partially dried and packed with salt, or allowed to swim in a salt-brine solution when packed for distribution. For a full range of traditional options, including hog, sheep, and beef varieties, explore our natural sausage casings collection.

Primary animal sources include:

• HOG (pig) - The default sausage casing we (and other retailers) simply sell as "Natural Hog Casings" is derived from the animal's small intestines, which are sometimes called "runners". Used in more than half of all commonly sold sausages (using natural casings) in the US, check your grocer's deli case and everyone's grills in the summertime, there are sausages made with hog casings inside. They can be made into rope sausage, links, and loops, with a natural, immediately recognizable curve. Large intestines, on the other hand, are called Hog Middles. These will still contain a large portion of the mucosal layer, which inevitably includes some fatty deposits in the crypts (see above). Although thoroughly cleaned, they do emit a pungent, 'natural aroma' that many people unfamiliar with hog middles dislike. To offset this smell, add a tsp of white vinegar per cup of water when soaking overnight, which helps tenderize and de-stink them. There is a lot of collagen material here as well.. these are often used under greater stuffing pressure, which is why these casings contain additional layers. Hog bladder, the original sous vide bags! Used for stuffing herbs, spices, whole pieces of meat, and offal organ meat for boiling or poaching. Also used for delicious charcuterie recipes like Culatello.
  
  
  
  
• Sheep - Small intestines, mostly the same as the above in regards to the popularity of the 'runners' for nearly all small diameter sausages, from breakfast sausage links, snack sticks, to hot-dogs! These casings tend to be on the more tender side and need a little bit of care when stuffing near capacity.
  
  
  
  
• Beef (cattle) - Known for having a complex ruminant gastrointestinal system that has the capability of breaking down and extracting nutrients from fibrous, high-lignin forage. The intestines of cows tend to be naturally more durable and structurally resilient when stuffed. But this also makes them more chewy for us, and more common for the casings to be peeled before eating. However, they can be pre-treated during soaking by adding a little vinegar and/or lemon juice to the water. Natural Beef Casings are, by default, just as both Hog and Sheep casings, the small intestines, "runners" or "Beef Rounds", which have a natural curve to them, making them perfect for recipes like ring bologna, kiszka, and other naturally curved style sausages. Beef Middles are the extracted, cleaned, and processed large intestine. They are consistent in length and diameter, and straight when stuffed, making them perfect for most salami and summer sausage recipes. Beef Bung is NOT what it sounds like! It is an extra-digestive, long, wide pouch (not quite a stomach) that ferments and further breaks down difficult foods. Beef bung on the market is usually either closed on one side (called 'cap' end) or the open side (called 'afterend'). Picture a sock, cut in half... the feet/toe side is the cap-end, and the open sides on either side are the 'afterend'.
  
  
  

Other animals, such as goats, horses, and wild game, are rarely used, since domesticated hog, beef, and sheep remain the most common in commercial production and home use due to their ready availability and regulation for quality.

Why Natural Casings Behave the Way They Do

Because natural casings' structure is made of collagen fibers arranged in a biological matrix, making them:

• Semi-permeable to smoke and moisture, providing a vibrant color from the smoking process while allowing moisture to pass from inside out, and keeping a barrier against becoming soaked if cooked by poaching.
• Expandable with meat stuffing, varying in durability, and more likely to burst.
• Perfectly adhere to the meat inside with protein-to-protein, forming a skin.
• They dry uniformly during curing recipes, more forgiving than other casings to temporary changes in the environment (air movement and humidity).
• They produce the traditional "snap!"

Brief Chemistry Lesson on pH and Tenderization!

Collagen has an isoelectric point around pH 7.2–7.8. At this pH, collagen fibers tend to expel moisture and tighten. Lowering the pH (through mild acid soaking) causes fibers to swell and relax. This is why adding lemon juice or vinegar to soaking water can tenderize natural casings. Give it a try next time you are soaking casings, if you've noticed that your final product tends to become a bit tough and chewy when cooked. Add 1 teaspoon of white vinegar or 1 teaspoon of lemon juice per 6-10 ounces of water to your bowl if soaking for a few hours in tepid water; scale back a little if soaking overnight in the refrigerator.

Be cautious, though:

• Too low a pH (below ~3) weakens fiber integrity.
• Over-acidification can cause blowouts.

We hope you find this helpful and your recipes benefit from making these subtle yet impactful changes to your process. Don't worry about flavor being affected by this type of chemical tenderizing; the vinegar smell/flavor will dissipate quickly, but if unsure or concerned, just give them a brief rinse before applying to your stuffing tube.

Collagen Casings: Engineered from Animal Hide

Collagen casings are also animal-derived — but more processed.

They are made from collagen extracted from:

• The corium layer of beef hides
• Bones
• Tendons
• Occasionally, pork, poultry, or fish sources

Once extracted, the collagen is:

1. Mechanically and chemically broken into a paste.
2. Filtered and refined.
3. Extruded through a die to form a uniform tube.
4. Dried and stabilized.

This extrusion process is why collagen casings are perfectly uniform in diameter. For consistent diameters and easy handling, our collagen sausage casings are available in both fresh and smoked varieties.

Types of Collagen Casings

Fresh Collagen Casings

• Thinner walls
• Designed for grilling or frying
• Not suitable for hanging in smokers

Processed / Smoked Collagen

• Thicker and stronger
• Designed to withstand hanging and heat
• Used for snack sticks and hot dogs

Collagen Rounds and Middles

• Dense and strong
• Often classified as non-edible due to texture, even though technically, collagen

Why Collagen Behaves Differently

Because collagen casings are reconstituted and dried:

• They are less permeable than natural casings.
• They lack natural curvature.
• They offer efficiency and consistency.
• They require little or no soaking.

They are engineered for production control rather than traditional texture.

Fibrous Casings: Plant Fiber Reinforced Tubes

Fibrous casings are made from:

• Regenerated cellulose
• Reinforced with fibers from the Abaca tree (Manila hemp)

Their structure resembles a strong paper or a tea bag.

They are:

• Inedible
• Highly durable
• Permeable to smoke and moisture

For larger diameter summer sausage and slicing applications, see our selection of fibrous sausage casings. Because they are reinforced with fiber, they tolerate tight stuffing pressures and large diameters.

They are commonly used for:

• Summer sausage
• Salami
• Bologna
• Pepperoni

Some fibrous casings include:

• Protein-lined interiors to improve adhesion during dry curing
• Easy-peel treatments for slicing applications

Cellulose Casings: The Mold for "Skinless" Sausage

Cellulose casings are made from:

• Wood pulp
• Cotton linters

Processed into viscose and extruded into clear tubing.

They are commonly used in mass production for hot dogs.

After cooking and smoking, the casing is mechanically removed, leaving a "skinless" sausage.

Stuff, smoke, and peel with ease — using cellulose casings from The Sausage Maker. Made for smoke permeability and portion control, cellulose casings require no refrigeration and are available in a variety of sizes to fit your specific needs. Whether you're producing sausage in small batches or at volume, these casings deliver convenience, performance, and consistent results. They are never intended to be eaten.

Plastic Casings: Polymer-Based Barriers

Plastic casings are made from synthetic polymers such as:

• Polyamide (nylon)
• Polypropylene
• Polyethylene

They are:

• Inedible
• Often impermeable to smoke and moisture
• Used for high-yield water-cooked meats

These casings prioritize moisture retention and uniform shape over smoke penetration.

Vegetarian and Plant-Based Casings

For those seeking non-animal alternatives, we also offer select vegetarian sausage casings designed for specific applications. The plant-based casings may be made from:

• Alginate (seaweed-derived gel)
• Carrageenan
• Starch-based polysaccharides
• Cellulose blends
• Konjac

Many are applied through co-extrusion systems, where the casing forms around the filling during production.

While suitable for dietary restrictions, they often lack:

• The snap of natural casing
• The char response of collagen
• The drying behavior needed for traditional cured sausages

Edibility: A Clear Breakdown

Edible:

• Natural casings
• Most strand collagen casings

Technically edible but often peeled:

• Thick collagen rounds and middles

Not edible:

• Fibrous casings
• Cellulose casings
• Plastic casings

Packages using non-edible casings are required to state:
"Remove casing before eating."

Shelf Stability and Storage Differences

Natural casings:

• Preserved in salt or brine
• Refrigeration recommended
• Freezing remains debated in the industry

Collagen casings:

• Shelf stable
• Store in airtight packaging
• Avoid extreme temperatures

Fibrous casings:

• Room temperature storage
• Soak before use

Material composition determines storage behavior.

Common Misunderstandings

• Natural casings do not add noticeable flavor; they enhance texture and smoke permeability.
• Not all collagen casings are edible.
• Plastic casings are never edible
• Freezing natural casings is debated and depends on the salting method and handling.

Final Takeaway

Sausage casings are not all the same, and they are not made the same way.

Some are carefully cleaned anatomical collagen layers.
Some are engineered collagen extrusions.
Some are plant-fiber composites.
Some are synthetic polymer films.

Understanding what they're made of explains why they behave differently during stuffing, smoking, drying, and cooking.

From experience, most casing problems come from misunderstanding the material, not from a defective product.

Once you understand what each casing is made of, you can choose and handle it correctly with confidence.