Editing Sausage casing (section)

==Natural casings==

=== Origin ===

Natural sausage casings are made from the [[Submucosa|sub-mucosa]] of the small intestine of meat animals,<ref name=usdaask>{{Cite web|url=https://ask.usda.gov/s/article/What-are-casings-made-of|title=AskUSDA|website=[[United States Department of Agriculture]]}}</ref> a layer of the [[intestine]] that consists mainly of naturally occurring collagen.<ref name=ripe>{{cite book |doi=10.1016/B978-0-12-384731-7.00137-9 |chapter=Sausage Casings |title=Encyclopedia of Meat Sciences |year=2014 |last1=Rust |first1=R.E. |last2=Knipe |first2=C.L. |pages=235–240 |isbn=9780123847348 }}</ref> In Western European cuisine and Chinese cuisine, most casings come from pigs, but elsewhere the intestines of sheep, goats, cattle and sometimes horses are also used. To prepare the intestines as casings, they are flushed, scraped and cleaned with water and salt by hand or with machinery; today they are primarily machine cleaned. The outer fat and the inner mucosa lining are removed during processing.<ref name=ripe /> They are salted to lower the water activity (which inhibits microbial growth) and preserve the casing.<ref name=ripe /> Natural casings have been used in the production of meat specialties for centuries and have remained virtually unchanged in function, appearance, and composition. US and EU [[organic food]] regulations only allow natural casings, which can be derived from non-organically raised animals as there are no large scale slaughter plants which handle and process only organic animals and sell their casings as certified organic casings. As a result, all large scale natural casing companies buy casings from around the world and send them to their selection facilities to be graded and packaged. There are four primary animal genera which are used to manufacture natural casings (although all [[mammal]]s raised for [[meat]] could potentially be used to produce natural casing): [[Cattle|cows]], [[pig]]s, and [[lamb and mutton|lambs]] and [[sheep]].

=== Appearance ===

Natural casing sausages are distinguishable from collagen or cellulose casings because of their irregularity, although high quality sheep and lamb casings can be almost indistinguishable from a collagen casing as they have no noticeable imperfections. The main difference is in the way they are twisted and linked which impacts the appearance of the final product and makes it easy to differentiate a hot dog using natural sheep or lamb casing vs collagen casing. The size and usage of natural casings are impacted by the animal they are derived from, the narrowest being [[lamb and mutton|lamb]] followed by [[sheep]] followed by [[pig]] followed by [[Beef cattle|beef]]. The size range for lamb is 14&nbsp;mm to 28&nbsp;mm in diameter (which is how casings are graded), the size range for sheep is 16&nbsp;mm to 32&nbsp;mm in diameter, the size range for pig is 28&nbsp;mm to 58&nbsp;mm in diameter, the size range for beef is 43&nbsp;mm to 65&nbsp;mm, although beef bung caps (which are not derived from the small intestine) have a size range of 115&nbsp;mm to 130&nbsp;mm.<ref name=ripe />

=== Processing ===

The process begins at the slaughter plant where "green" (uncleaned) runners (ungraded casings) are removed from the animal during the slaughter process. They are subsequently cleaned, which involves breaking the inner mucosa, usually with a machine that the runners go through and rollers to break the inner mucosa so it can be flushed out and removed. The cleaning process can also be done by hand but primarily casings are machine cleaned. This is a very water intensive process as the casings are vigorously flushed with cold water to remove blood from the mucosa which if not properly flushed during the initial processing can lead to "staining" of the casing where it becomes pink. The cleaned runners are then tied in bundles and packed in plastic drums and filled with a saturated salt brine for preservation. The runners are then sold to a company which processes natural casings by grading and packaging them to create finished units called hanks.

[[File:Porto -i---i- (40099674775).jpg|thumb|upright|Sausage casings]]
Natural casings are produced and sold almost exclusively by the hank which is a unit of measure that is 91 meters long.<ref name=ripe /> A hank can consist of a varying number of strands (individual pieces of casing) which vary in length from 2 meters (which is the shortest length sold for commercial use) to as long as 28 meters. Each casing manufacturer has various "put ups" which dictate the maximum number of strands and the minimum length of each strand allowed in the put up. Casings are selected for size which is measured in millimeters and refers to the diameter of the casing; this is done exclusively by hand and is primarily done in China due to the availability of low cost labor. Commercially casings are available in various forms of packaging which are suited to different applications. Sheep/lamb and hog are available in all packaging types due to the high demand and long length of pieces; due to the shorter length and much lower demand for beef casings they are primarily only available loose or in net packs either salted or in brine.

=== Packaging ===
[[file:Hog Casings Packed in Salt.jpg|right|thumb|200px|Hog casings, packed in salt, from a vacuum pack]]
Sheep and lamb and hog casings are available "tubed" where each strand is put on a plastic tube which allows the sausage maker to easily place the casing on the stuffing horn;<ref name=ripe /> in recent years these tubes have been modified so they break open along a seam and the operator can pull them out at the back of the horn allowing greater efficiency; these are referred to in the industry as "zip tubes", due to the zipper-like nature of the seam. These tubed casings are then packed in plastic nets, usually two per net, and packed in plastic drums, which are then filled with a [[Saturated solution|saturated]] salt [[brine]], usually 200 per drum. These are available in all diameters and in lengths greater than 3 meters (as 2-meter or shorter pieces are cost prohibitive to tube).

Sheep, lamb, and hog casings are also available loose in brine in a vacuum sealed plastic pack; commonly referred to as "vacuum packs", these are primarily used by small- to medium-sized sausage makers who use less than 100 hanks per month of casing. The appeal of vacuum packs is the ease of use, their shorter strand length for hand stuffing (all sausage makers who do not use automatic sausage stuffing and linking machines) and their shelf life; they only need to be opened as needed so the sausage maker does not need to worry that they will not use their opened casings prior to a decrease in quality. These are available in all diameters and in put ups from short up to medium length, about 6 meter minimum, with a maximum length of about 14 meters.

Sheep and lamb and hog are also available in a net, commonly referred to as net pack. These are available salted or in brine and they are primarily used by medium to large sausage makers who do not want to pay the additional cost for the tubed casing and do not have automatic sausage stuffing and linking machines (which require tubed casings to operate efficiently). These are available in all diameters and in lengths greater than 2 meters (as that is the shortest length sold for commercial use).

Beef casings are primarily available only salted or in brine. They are measured in sets, not hanks, and the length is 32 meters; this is for beef "rounds" and "middles" only, as beef bung caps are only about 1 meter in length.