Editing Sausage casing (section)

==Inedible casings==

Casings made from cellulose and plastics are peeled off food products and are not eaten.<ref name=usdaask />

===Cellulose casings===

Cellulose, usually from cotton linters or wood pulp, is processed to make [[viscose]], which is then extruded into clear, tough casings for making [[Hot dog|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 or for example [[abaca]] pulp to make large diameter fibrous casings for [[Bologna sausage|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 treatments.

===Plastic casings===
[[File:Bilyan Factory, Armenia 07.jpg|thumb|Plastic casings in use at Bilyan Factory, Armenia (2007)]]
[[File:Bilyan Factory, Armenia 02.jpg|thumb|Bilyan Factory]]
Plastic casings are not eaten.<ref name=usdaask /> They also can be flat or shirred. Generally, smoke and water cannot pass through the casing, so plastic is used for non-smoked products where high yields are expected. The inner surface can be [[laminated]] or co-extruded with a polymer with an affinity for meat protein causing the meat to stick to the film, resulting in some loss when the casing is peeled, but higher overall yield due to better moisture control.

Plastic casings are generally made from polymers such as [[polyamide]], [[polypropylene]], or [[polyethylene]]. Polyamide (Nylon) plastic casings are the most commonly used in production of cooked sausages and hams such as luncheon meat and bologna. Polyamide casings come in two main varieties: Oriented and non-oriented. The oriented polyamide<ref>{{Citation|last=Vicik|first=Stephen James|title=A heat shrinkable polyamide sausage casing with a polyolefin core layer|date=Dec 11, 2002|url=https://patents.google.com/patent/EP0589436B2|access-date=2016-11-10}}</ref> are shrinkable casings and will shrink during the cooking process thereby reducing the water loss. Non-oriented polyamide casings remain the same diameter during the cooking process and thereby allow for expansion of the meat during cooking. The use of polyamide casings has expanded recently with the advent of various varieties and structures of casings such as multilayer casings.<ref>{{US patent|4243074}}</ref>