Casings are an important part of any sausage product. Along with often adding flavor, they help create the shape, aid in cooking and keep the meat mixture inside together.

“Casings are used to shape and contain meat and poultry products ranging in size from full-muscle blends to finely ground emulsions,” says Shawn Brammall, director of technical services at J Bar B Foods. “Some casings are designed to allow the product to be permeated — for instance with smoke — while others are designed to be totally non-permeable so that no loss occurs during the cooking process.”

The type of casing used depends on what type of sausage is being made. Casings can be both edible and inedible. If it is a casing that cannot be consumed, it is usually removed after the product is cooked and before the product is sold.

Edible casings typically include those made from small intestines of animals, collagen or vegetable products. Cellulose and plastic casings, on the other hand, must be removed after cooking.

Michael Clabby, principal scientist for Sara Lee Food and Beverage, says that these natural casings and cellulose casings are used with hot dogs and sausages, with the natural casing being used with the traditional versions. Plastic casings are limited to use with cooked ham and lunchmeats such as bologna and salami.

Cellulose is very common today as a casing for cooking and transferring flavor.

“Cellulose casings are used for hot dogs or franks,” explains Deb Herman of ConAgra Foods, which owns Hebrew National. “Cellulose is the main component of higher plant cell walls and one of the most abundant organic compounds on earth. It allows the hot dogs to lose moisture and develop the desired texture.”

Hebrew National, which produces kosher sausage, has always used cellulose casing. Other companies with different products and markets will use natural casings.

“Originally, casings came from the small intestines of animals,” said Clabby. “Hog intestines were used for sausages and sheep intestines were used for hot dogs. The determination was based on size. Sausages tend to be larger in diameter than hot dogs. Therefore, the sausage casings usually came from hogs.”

With the variety of casings available today, the type used depends on the product being produced. Brammall says all sliced sausage products use an inedible casing that can be removed before or after slicing.

 “If you add skinless hot dogs and sausages to the sliced meat categories, the use of inedible casing far exceeds the use of edible natural, collagen, and vegetable casings,” Brammall adds.

Clabby says cellulose casings are much less expensive than natural ones and are more efficient for use in manufacturing facilities.

J Bar B, for its part, specializes in natural and co-extruded sausages, with the majority being hog and sheep intestines. For “skinless” sausages, the company uses cellulose that is peeled off after cooking and chilling. it also uses a fibrous casing the is removed by the consumer for products such as summer sausage.

“There are also a number of cook-in [non-permeable] casings made from polymers that come in a number of sizes and colors,” Brammall says.

When used for cooking, cellulose casings can help with the flavor.

“Cellulosic casings do not transfer flavors [of their own,]” says Hermann. “In fact, the casing is natural, but the casing has tiny pores which allow the smoke to permeate the hot dog’s surface and, under thermal processing, impart flavor and texture.”

While casings are useful in different parts of the sausage making process, their main purpose is also the most basic. They help the sausage retain the well-known sausage shape.

“Casings are basically a container to create the shape that we have come to know as a hot dog,” says Clabby. “The hot dog mixture is pliable before it is cooked, similar to a meatloaf or cake batter.”

As a cook will use a meatloaf pan to give the meatloaf its traditional shape, a processor will use the casing to do the same for the hot dog.

Systems used today, while not necessarily the same ones used when sausages were first made, are designed to duplicate the traditional curved link and ring sausages, systems that processors such as J Bar B have readily adopted to make the process more efficient without sacrificing the traditions with which consumers have become familiar and comfortable.

“There are several key factors in choosing the right casing for a given application,” says Brammall. “The first thing to decide [is] whether the product is going to be skinless, have an edible casing, or non-edible casing removed by the customer. The next decision is whether the product needs to be smoked or colored.”

After that, he says, the choice is whether the product will be smoked or flavored. That will determine if a permeable or non-permeable casing is used. For a product that will be smoked, cellulose, natural or other permeable casing needs to be used to allow the smoke into the meat. For color, a permeable casing that will either transfer color or is colored and consumed with the product.

If the casing is to be removed by the consumer, then a non-permeable casing that eliminates cook shrinking and increases shelf life may be preferable. Impervious casing can also be coated with color and/or flavors, which transfer from the casing to the product, Brammall says.

“One of the newest developments in casing is the advent of new co-extrusion lines. Now there is a greater choice than ever in co-extrusion casing materials,” continues Brammall. There is the traditional beef collagen, which was first used in Europe probably about 20 years ago. Now there are pork collagen and alginates for fresh and cooked co-extruded products.”

While most associated with different types of sausages, such as hot dogs or kielbasa, casings can be used on a variety of meat products.

“Casings are used on almost all meat type of products,” says Brammall. “The primary non-sausage casing use would be for smoked/cooked meat and poultry products, both whole muscle and chunked and formed.”

Many processed meats also are made with casings to help give them their shapes.

Cooking with casings is more dependent on personal and, in some cases, regional taste.

“We’re from Texas, so they gotta be grilled!” declares Brammall.

Hermann of ConAgra says that summer favorite hot dogs can be cooked in several ways: in the microwave, on the stovetop, grill or on roller grills in stadiums.

“The cooking process is determined by the size and appearance attributes that the customer requires,” says Clabby. “The casing creates a product that is consistent in size and shape. Therefore, it assists in a consistent cooking process.”

The snap that some sausages and hot dogs are known for can actually depend on different factors.

Hermann says at Hebrew National, the snap comes from the type of meat, ingredients and how the product is cooked. The company’s hot dogs are made with cellulose casings with the skin removed before it is sold.

Brammall says that the snap that a particular manufacture will try to achieve also depends much on the consumer group that tests the sausage.

“Snap level depends on the region and preference of the end user,” explains Brammall. “J Bar B designed its new co-extruded products to have a firm bite snap, like a natural sheep casing, but with less bite than hog casings. The goal was to give the consumer the feel of natural casing without the chewy texture. Other processors have opted to skinless casings because their customers do not want the snap of a natural casing.”