Excerpt from a post in the AfricaHunting.com Forum, to read the full thread click here.
The last post dealt with making sausage blends. If we've done that correctly, now we need to stuff them into something... a casing!
There are a number of casing types available, but each is specific to a type of sausage and its intended use. Here's some explanation of the more common types, how to prepare them for use and how to stuff them.
Fibrous casings are not edible (peel off prior to eating) and are made out of paper. Specifically, they are made of the exact same kind of paper used to make tea bags. Why? Because that type of paper won't break down when it gets wet, but is PERMEABLE to moisture. Fibrous casings are most often used for dry or semi-dry, ready-to-eat, fully cooked sausages like summer sausage, pepperoni and salami. With each of these sausages, drying is an important part of the manufacturing process, so the ability of water to move through the casing and OUT of the product is very important.
Similarly, smoke can penetrate IN through fibrous casings and the addition of smoke is important to flavor development and preservation. (More on this when we get to cooking and smoking...)
This casing type is available in diameters ranging from 1" up to about 8", but the most extreme diameters are not readily available to the home sausage maker. The most common sizes that are easy to obtain (google "home sausage maker") range from 1.5" to 3" in diameter. Fibrous casings can be "clear" (no coloring added to the paper) or can come in a variety of colors ranging from mahogany to yellow to bright red. Only the clear casings will let you know how much smoke color is developing on the surface of the product, so I always recommend them for home sausage makers.
The casings can be treated to easily release from the sausage or adhere tightly. The EZ-peel varities should be used for sauages requiring only a moderate amount of shrink (thuringer or summer sausages), the tight-adhering should be used for sausages that require high amounts of drying (greater than 20% weight loss) so that they stay "stuck" to the product during the entire drying process. When you purchase the casings, be sure to ask about adhere-release properties and choose the type appropriate to the sausage you are making.
Fibrous casings can be purchased in a few different offerings:
• "Flat Stock" - this is just a paper tube with no closure on either end. You will have to tie or clip one end shut before stuffing.
• "Clipped" - one end is crimped closed with an aluminum staple (sausage makers refer to these staples as "tipper ties", or "poly clips")
• "Stringed and Capped" - one end is closed with a crimped aluminum cap and a string is attached that makes the stuffed casing easy to hang in the smoke house
• "Shirred" - a very long piece of casing (up to 100 feet) is bunched up into a long tube for use on automated stuffing equipment. Unless you have a buddy in the meat business, these are pretty hard to obtain
For the home sausage maker, the stringed and capped are the handiest to use, they are also the most expensive. The good news is that they are very unlikely to fall off the smoke rod if you purchase them from a reputable company.
The internal coating on fibrous casings can get moldy if the casings get damp, so always keep them dry and in a sealed plastic bag so they don't pick up moisture.
All fibrous casings should be soaked in warm (100 degrees F) water for at least 10 minutes before use. Unused soaked casings should be thrown away because of the molding potential. Fibrous casings are expensive, so only soak the amount you will need.
When stuffing fibrous casings using a bench-top stuffer, there are only two things to remember: STUFF THEM TIGHT and HAVE SOMEONE HELP YOU. I cannot emphasize tight stuffing enough. You want them so tight that they feel as if they will burst. Hold the casing on the stuffing horn as tight as you can while someone else cranks the stuffer. When stuffing the casings, leave enough "tail" so you can twist the sausage chub to put even more pressure on it, then have your partner tie off the casing with a piece of butcher's string. If you don't bust one or two of the casings when twisting and tying, you are not stuffing tight enough.
The reason for the emphasis on tight stuffing is that mechanical compression really improves the "bind" sausage during the fermenting and/or cooking processes. Good bind translates into good firm texture in the finished sauage.
Collagen casings are made from animal connective tissue protein. Specifically, they are made from the inside (corium) split of beef hides. Chemically, they are identical to Jell-O.
The casings are made by dissolving the beef hides in acid and caustic solutions followed by heat extraction. The dissolved collagen is then extruded in the form of a tube that is "set" by passing through solutions of concentrated salts followed by oven drying.
Depending on the chemical treatment of the collagen in the extraction and extrusion processes, the properties of the casings are tailored to 3 different sausage applications:
FRESH SAUSAGE COLLAGEN (like breakfast links)
These casings are designed to be tender (cut with a fork) and to partially dissolve when heated. Never try to use this type of casing for fully cooked sausages. As soon as they are exposed to heat and humidity in the smokehouse, they will begin to melt and all your sausage will fall off the rack!
The most common brand names for fresh sausage collagen casings are "Super Fry" and "Coria". Fresh sausage collagen casings are premoistened at the factory and are hermetically sealed in foil covered boxes. They should be stuffed only tight enough to expand the casing to full diameter. This type of casing is available in diameters ranging from 16mm to 22mm
Unused casings should be put back into sealed plastic bags and kept refrigerated. An unopened box of this casing type has a shelf-life of about a year. After a casing box is opened, the shelf life of the casings is about one month if kept sealed and refrigerated.
SMOKED/COOKED SAUSAGE COLLAGEN (smoked sausage, semi-dry snack sticks, etc.)
These casings are edible and designed to hold up to the cooking process without dissolving. They are also formulated so that smoke will adhere to them and to bind to the sausage batter during the cooking process. They are available in diameters of 14 to 18mm for snack sticks and 22 to 30mm for smoked or cooked sausages.
Some of the common commercial brands cooked sauage collagen casings are "Brechteen", "Nitta", "Cutesin" and "Nippi". They can be packed like the premoistened fresh sausage collagen casings or can be packed as completely dried casings. If premoistened, the storage requirements and limits are the same as for the fresh casing. If packed completely dried, they can be held for up to a year.
Fully dried casings in this category should be dipped into warm water for a few seconds prior to stuffing. Premoistened casings do not need to be soaked.
When stuffing this type of casing for rope sausages or snack sticks, stuff as tightly as you can without breaking the casing. When stuffing for links, stuff a little looser so that the links can be twisted to tighten the casing. For both types of stuffing, tie the ends shut with an overhand knot.
FIBROUS COLLAGEN CASINGS
These are NON-edible casings that have to be peeled off prior to eating the sausage. The most common uses are for making ring bolognas and liver sausages like braunschweiger.
Preparation and stuffing methods are the same as for dried smoked sausage collagen casings described above.
Natural casings are sections of the intestinal tract of animals. Chosen and prepared correctly, they are the ultimate casings for sausages that could end up on the grill. Unlike manufactured casings, they don't tend to surface-burn when exposed to the very high heat of a charcoal fire. Bung sections of beef intestine can also be used for large diameter sausages like bolognas.
Natural casings can be harvested from animals taken or slaughtered, but proper preparation is essential. Outlining the procedures is not the purpose of this post, so I will deal just with commercially available natural casings. (If there is a lot of interest, I can do a later post on how to prepare and preserve natural casings.)
This post will deal with the two most common types and uses of natural casings.
Lamb casings range in size from 18-26mm, although the larger end of the range is pretty rare today. Lambs are mostly all slaughtered at light weights due to market demand and these animals still have very narrow intestinal tracts. Lamb casings are ideal for making wieners and other small-diameter cooked sausages and are great for making semi-dry, shelf stable snack sticks. Smoke color and flavor adheres to natural casings far better than any other casing type. Lamb casings are also commonly used for small-diameter fresh Italian sausage.
Hog casings can range in diameter from about 28mm up to about 40mm. Generally, the narrower the diameter, the more tender the casing. Hog casings are ideal for making rope or linked smoked sausages. They are also the best casings for making raw grilling sausages like fresh bratwurst or fresh Polish.
All natural sausage casings are packed in a concentrated salt brine and then covered with food-grade salt to preserve them. While refrigeration of the salted casings is not required, it does help them keep for a longer period. Shelf life of salted natural casings is about 2 years.
Preparation for all natural casings is the same: Rinse thoroughly in luke warm running water until all visible salt is gone. Then soak in cold water for 1-2 hours. Re-rinse and flush with cold water (run water throught the casing) just prior to use.
When using natural casings for any type of cooked/smoked sausages, the stuffing procedures are the same as those for smoked/cooked collagen casings.
When using natural casings for fresh sausage, follow the same stuffing procedures as for fresh sausage collagen casings.
Re-storage of rinsed & soaked natural casings requires that they are properly re-salted. This is best accomplished by soaking the casings overnight in a completely dissolved solution of 2 pounds of salt in 10 pounds of water. After the overnight soak, keep the casings in the brine, but also cover them with a 1/2 inch of salt. Keep the re-salted casings in a sealed container.
OTHER CASING TYPES
There are other types of casings such as regenerated cellulose (used for skinless wieners) and plastics (used for deli luncheon meats) and barrier fibrous (used for braunschweiger).
The next post will deal with fermentation, smoking and cooking.
The author, browningbbr, has a degree in Animal Science from Iowa State University (specialized in meat processing) with minors in Food Science and Food Technology. He has an M.S. in Food Science from Oklahoma State University through the Department of Animal Science, again specialized in meat processing.
For the last 30 years, he also experimented on the best ways to handle the processing of wild game to get the best quality meat for the table. When in South Africa, he asked a LOT of questions about how meats are processed, handled and prepared there. The hunting outfitter and chef gave him many insights into their procedures. Not suprisingly, the most effective ones matched basic principles of good meat science.