Today, CASING RECOVERY - most often done in large slaughtering facilities - is both a precise science and an elaborate process. It requires high-level expertise, state-of-the-art machinery, and maximum sanitation and quality control procedures.

As the intrinsic value of the raw material represents a large part of the finished casing product, every inch of tract needs to be utilized. In the slaughterhouse, the viscera of each animal is removed, and the various parts of the intestinal tract are separated. This separation of parts is instrumental in creating a variety of products ranging all the way from pig chitterlings to sheep appendixes for pharmaceutical products.

The casings are prepared for the removal of manure, mucosca (raw material for the anticoagulant "heparin") and any undesirable elements such as fat, threads and animal fluids. This removal, facilitated in a series of both hot and cold water soaks, is accomplished by machine crushing under close "hands-on/eyes-on" scrutiny.

The fully cleaned casings are placed in a saturated salt environment to prepare for further processing. The casings are then sorted into various grades and diameters. The selection process is dictated by such factors as: type of animal, and criteria set by the casing processor and ultimately the sausage producers.

Measuring Casings - After selection, all casings are carefully measured, either by machine or by hand. Regardless of measurement method, both must be accurate since the measured unit becomes the sales pricing criterion.

Hog Casings and Sheep Casings are prepared in 91-meter (100 yard) hanks or bundles. Beef Casings, if not sold by the piece, are sold in 18-30 meter bundles for Beef rounds, and 9-18 meter sets for Beef Middles.Determining Quality - Qualities are determined in several precise and labor-intensive ways.

In sheep, for example, an "A" quality casing is determined during selection, and is defined as a casing with no holes or weakness. This casing can be used for the finest frankfurter emulsion. "B" quality casings are of acceptable strength and quality for coarse ground emulsions such as those used in Pork Sausage.

With Beef Casings, the term "Export Quality" is sometimes used. This term describes casings as free of nodules (pimples) or scores (windows).

With Hog Casings, there is a single quality standard with several specifications for length. Where the various hog casings originate from - taking into consideration factors of species, climate, and diet - will generally determine the different characteristics of the casings. Some will be "white" or virtually transparent / clear; others will be darker and more opaque and will have more visible veining. These characteristics also have an effect on the tenderness or "bite" of the casing.

Clear Hog Casings are generally used for fresh products. Thicker and stronger casings such as Chinese Hog Casings are generally best suited for smoked products, because these casings better withstand the smoking process and because casing appearance is not as critical a selling feature, due to the smoking process itself.

Test Procedures - The traditional methods for grading and testing Natural Casings are: water testing for Sheep and Hog Casings, and air testing for Beef Casings.

The casings are appropriately filled with water or air and periodically expanded under pressure, to check for size and quality. The casings are then cut to final sizes and quality specifications are confirmed during quality control.

Shipping Casings - Casings are prepared and preserved in various forms for shipping to the sausage makers, Some Examples include:

  Dry Salt Pack: Excess moisture is removed for semi-dry state. This is usually appropriate for long distance travel and/or prolonged storage at ambient temperatures
  Slush or Preflushed Packed: In this convenient form, casings are very soft and flexible and do not require flushing prior to use
  Pre-tubed Casings: Each strand is shirred on a tube to allow one-step loading of the casing directly on the sausage filling horn - without the need for flushing - by the processor

Casings should be stored in a controlled, cool environment. Special care should be taken to avoid excessive heat. A neutral temperature of 4-10 Deg. C (40-50 Deg. F) is ideal.