Edible collagen sausage casings made their debut in the 1920s as an alternative to natural casings--the intestines of cattle, sheep and pigs. They are processed from proteins in animal hides. You can use them in much the same way as natural casings, but there are a few differences.
Buy the Right Size
Collagen casings, like the natural versions, come in three diameters: The smallest, at about three-quarters of an inch, is for frankfurter-size sausage; the 1-inch variety is best for kielbasa and bratwurst; and the largest size, about 1.75 inches, is for summer sausage.
Don't Soak Them
You can use collagen casings straight from the package, unlike natural casings, which have to be rehydrated before you stuff them.
Threading the Tube
Thread several feet of casing onto the barrel of your stuffing tube--push it on with a pleating motion, like pushing the sleeve of a sweater up your arm. Pack it on well, because you don't want to have to stop and reload it partway through the stuffing process.
Collagen casings are not as stretchable as the natural variety--they split when they are too full. (But don't fill too loosely, or the casing won't adhere to the meat mixture.) The sausage should feel full, but as if you could get a little bit more in there. You will develop a feel for it.
Some sausage makers create links with four or five gentle twists, which is the time-honored method with natural casings. Collagen tends to untwist, however. To prevent that, many sausage makers tie each link with butcher's twine.
Keep It Cool
You do not have to refrigerate collagen casing, but keep it sealed up in a cool, dry place. It will keep for as long as 18 months.