Sausage casing facts for kids

Sausage casing, also known as sausage skin, is the outer layer that holds a sausage together. Think of it like the wrapper for a hot dog or a salami! There are two main types: natural casings, which come from animals, and artificial casings, which are made by people. Artificial casings started being used in the early 1900s.

Natural Casings: From Animals

Where Do Natural Casings Come From?

Natural sausage casings are made from a special part of an animal's small intestine. This part is called the sub-mucosa, and it's mostly made of a natural material called collagen. In many parts of Europe and China, these casings usually come from pigs. But in other places, they can also come from sheep, goats, cows, or even horses.

To get the intestines ready, they are carefully cleaned with water and salt. This process removes any fat and inner lining. The salt helps keep them fresh by stopping tiny germs from growing. Natural casings have been used for hundreds of years and still work the same way today. Rules for organic food in the US and EU say that only natural casings can be used.

What Do Natural Casings Look Like?

You can often tell a sausage with a natural casing from one with an artificial one because natural casings are not perfectly smooth. They might have small bumps or twists. However, very good quality sheep or lamb casings can look almost perfect, just like artificial ones.

The size of a natural casing depends on the animal it came from. Lamb casings are the smallest, then sheep, then pig, and finally beef. Lamb casings are usually about 14 to 28 millimeters wide. Sheep casings are 16 to 32 millimeters wide. Pig casings are much wider, from 28 to 58 millimeters. Beef casings are the widest, from 43 to 65 millimeters.

How Are Natural Casings Made?

The process starts at the place where animals are prepared for meat. The intestines, called "runners," are taken out. Then, they are cleaned. This usually involves machines that gently break up the inner lining so it can be washed away. Lots of cold water is used to make sure all the blood is removed, which stops the casing from turning pink.

After cleaning, the runners are tied into bundles. They are then put into plastic drums filled with salty water. This salty water helps keep them fresh. These cleaned runners are then sold to companies that specialize in natural casings. These companies sort and package them into finished units called "hanks."

A hank is a measurement unit for casings, about 91 meters (or 300 feet) long. A hank can have different numbers of individual pieces of casing, called "strands." These strands can be from 2 meters to 28 meters long. Casings are sorted by their size, which is their diameter in millimeters. This sorting is often done by hand.

How Are Natural Casings Packaged?

Natural casings are packaged in different ways for different uses.

• Tubed Casings: Sheep, lamb, and pig casings can be "tubed." This means each strand is put onto a plastic tube. This makes it easy for sausage makers to slide the casing onto their machines. Some tubes even have a "zip" feature that makes them even easier to use. These tubed casings are often packed in salty water in large drums.
• Vacuum Packs: These casings are loose in salty water and sealed in plastic vacuum packs. They are great for smaller sausage makers because they are easy to use and stay fresh until opened.
• Net Packs: These casings are available either salted or in salty water, packed in a net. They are used by medium to large sausage makers who don't need the special tubes.

Beef casings are usually just salted or kept in salty water. They are measured in "sets" instead of hanks, and a set is about 32 meters long.

Artificial Casings: Man-Made Wrappers

Artificial casings are made from materials like collagen (often from animal skin), cellulose, or plastic. Some artificial casings, like many collagen ones, can be eaten. Others, like cellulose or plastic, are usually peeled off before you eat the sausage.

Collagen Casings

Collagen casings are mostly made from the collagen found in cow or pig hides, bones, and tendons. They can also come from poultry or fish. These casings have been around for over 50 years and are becoming more popular. It's often cheaper to make sausages with collagen casings because the machines can work faster, and less human effort is needed.

The collagen for these casings goes through a lot of processing. It's pushed through a special shape to get the right size. Then, it's dried and gathered into short sticks, about 41 centimeters (16 inches) long. Each stick can hold up to 50 meters (164 feet) of casing! Some newer methods even make the casing right as the meat is being put into it.

The newest collagen casings are usually softer than natural ones. They might not have the same "snap" when you bite into them. Most collagen casings are safe to eat. However, some thicker collagen casings are used for large sausages like salamis. These are usually peeled off by the person eating the sausage. Collagen casings are often cheaper, help control the size and weight of the sausage better, and are easier to use in machines.

Vegetarian Casings

In recent years, new ways have been found to make casings entirely from plants. These are called vegetarian casings. Special machines are needed to make these casings, which can be used for foods that follow halal or kosher rules.

Casings You Don't Eat

Some casings, like those made from cellulose or plastic, are not meant to be eaten. They are peeled off the food before you enjoy it.

Cellulose Casings

Cellulose casings are made from plant materials like cotton or wood pulp. This material is processed and then pushed out into clear, strong casings. These are often used for hot dogs and frankfurters. They are also gathered into short sticks for easy use. Sometimes, they are dyed to make "red hots." After the sausage is cooked, the casing is peeled off, which is why you see "skinless" hot dogs.

Larger cellulose casings are made by combining cellulose with wood pulp. These are used for big sausages like bologna or smoked ham, which are often sliced for sandwiches. These casings let smoke and water vapor pass through them, which helps with flavoring.

Plastic Casings

Plastic casings are not eaten. They can be flat or gathered into sticks. Generally, smoke and water cannot pass through plastic casings. So, they are used for sausages that are not smoked. The inside of some plastic casings can be treated so the meat sticks to them. This helps keep the sausage moist and can lead to less waste when the casing is peeled off.

Plastic casings are usually made from types of plastic like polyamide (also known as Nylon), polypropylene, or polyethylene. Polyamide plastic casings are very common for cooked sausages and hams, like luncheon meat. There are two main kinds of polyamide casings: those that shrink when cooked and those that don't. The shrinking ones help reduce water loss during cooking. The non-shrinking ones allow the meat to expand. More and more types of plastic casings are being made, including ones with many layers.

Images for kids

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  Sausage casings

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  Hog casings, packed in salt, from a vacuum pack

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  A salami and the collagen casing (below) it came in

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  Plastic casings in use at Bilyan Factory, Armenia (2007)

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  Bilyan Factory