Sausage CasingsCasing, sausage casing, or sausage skin is the material that encloses the filling of a sausage. Casings are divided into two categories, natural and artificial. Artificial casings, such as collagen, cellulose
and extruded casings, are relatively new to the field, mainly borne of
market demand during the technological advances of the early 20th
It is often assumed that sausages were invented by the Sumerians in the region that is Iraq today, around 4000 BC. Reference to a cooked meat product stuffed in a goat stomach like a sausage was known in Babylon
and described as a recipe in the world’s oldest cooking book 3,750
years ago (Yale Babylonian collection, New Haven Connecticut, USA).
The Chinese sausage làcháng, which consists of goat and lamb meat, was first mentioned in 589 BC. The Greek poet Homer mentioned a kind of blood sausage in his Odyssey (book 20, poem 25); Epicharmus (ca. 550 BC — ca. 460 BC) wrote a comedy entitled The Sausage. Numerous books report that sausages were already popular among the ancient Greeks and Romans.
Natural sausage casings (“casings”) are made from the sub-mucosa, a layer of the intestine
that consists mainly of naturally occurring collagen. This should not
be confused with collagen casings, which are artificially processed from
collagen derived from the skins of cattle. Natural casings are derived
from the intestinal tract of farmed animals, are edible
and bear a close resemblance to the original intestine after
processing. The outer fat and the inner mucosa lining are removed during
Natural casings are traditional products that have been used in the
production of meat specialties for centuries and have remained virtually
unchanged in function, appearance, and composition. Salt and water are
all that is used for cleaning and preservation. Natural casings are the
only casings that can be used in organic sausage production.
A large variety of sausage is produced world-wide using intestines of
pigs, sheep, goats, cattle and sometimes horses. Although the
intestines were previously flushed, scraped and cleaned by hand, more
recently, machinery has been used for large scale production.
Natural casings breathe, allowing smoking
and cooking flavors to permeate the casing and infuse the meat, giving
the sausage a rich, even flavor throughout. Natural casings have unique
natural curves and sheen, with rounded ends where the sausage is linked
giving the sausage visual appeal.
Due to their non-uniform appearance, sausages stuffed in natural
casings are clearly distinguishable from mass-produced products and are
therefore acceptable as a higher quality, premium product. However,
newer machinery has enabled sausage producers to develop mass production
scales of efficiencies in their processing plants. Processors of
natural casings have developed long-stranded casings with uniformity and
strength to support this new technology, as well as new tubing
(Shirring) systems that speed up the stuffing process. This has
revolutionized the sausage manufacturing world and kept natural casings
preferred by some manufacturers and consumers.
Artificial casings are made of collagen, cellulose, or even plastic
and may not be edible. Artificial casings from animal collagen can be
edible, depending on the origin of the raw material.
Collagen casings are mainly produced from the collagen in beef or pig
hides, and the bones and tendons. It can also be derived from poultry
and fish. They have been made for more than 50 years and their share of
the market has been increasing. Usually the cost to produce sausages in
collagen is significantly lower than making sausages in gut because of
higher production speeds and lower labor requirements.
The collagen for artificial casings is processed extensively and, as a
raw material, it is similar to bread dough prior to final production.
It is then extruded
through a die to the desired diameter, dried and shirred into short
sticks up to 41 cm long that contain as much as 50m of casing. In a
newer process, a form of dough is coextruded with the meat blend, and a
coating is formed by treating the outside with a calcium solution to set
The latest generation of collagen casings are usually more tender
than natural casings but do not exhibit the “snap” or “bite” of natural
casing sausages. The biggest volume of collagen casings are edible, but a
special form of thicker collagen casings is used for salamis
and large caliber sausages where the casing is usually peeled off the
sausage by the consumer. Collagen casings are permeable to smoke and
moisture, are less expensive to use, give better weight and size
control, and are easier to run when compared to natural casings.
Cellulose, usually from cotton linters or wood pulp, is processed to
make viscose [a caustic-soluble xanthan salt] which is then extruded
into clear, tough casings for making wieners and franks. They also are shirred
for easier use and can be treated with dye to make "red hots". The
casing is peeled off after cooking, resulting in "skinless" franks.
Cellulosic viscose solutions are combined with wood pulp to make large
diameter fibrous casings for bologna, cotto salami, smoked ham and other
products sliced for sandwiches. This type is also permeable to smoke
and water vapor. They can be flat or shirred, depending on application,
and can be pretreated with smoke, caramel color, or other surface