Casing by Deepak Yadav
Channel: CHITKARA UNIVERSITY RESEARCH & INNOVATION NETWORK
Date: 2020-08-17

Natural sausage casings are made from the sub-mucosa of the small intestine, a layer of the intestine that consists mainly of naturally occurring collagen. 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. They are salted to lower the water activity (which inhibits microbial growth) and preserve the casing. 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, they 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 three primary animal species which are used to manufacture natural casings (although all mammals raised for meat could potentially be used to produce natural casing): cows, pigs, and lambs and sheep.

The process begins at the slaughter plant where "green" (uncleaned) runners (ungraded casings) are removed from the animal during the slaughter process and they are subsequently cleaned, which involves breaking the inner mucosa usually with a machine that they go through and rollers 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 the company which processes natural casings by grading and packaging them to create finished units called hanks.

Natural casings are produced and sold almost exclusively by the hank which is a unit of measure that is 90 meters long. 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 millimetres 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.