Natural casings meet the same high quality standards as fresh meat.


Natural sausage casings companies must comply with Hazard Analysis Critical Control Points (HACCP) requirements. The HACCP system ensures food safety.

Natural casings companies have developed an HACCP manual for processing of natural sausage casings, in close association with international organisations. The manual was originally published by European Natural Sausage Casing Association (ENSCA). It was compiled by Dutch and German scientists, and lists, in separate chapters, the critical points for each type of company.
The company types are:

  • Casing processing companies, which process fresh casings in slaughterhouses, also called cleaning companies.
  • Sorting companies, which sort casings on the basis of quality, calibre and length.
  • Distribution companies, which trade natural casings without further processing.

The critical points for natural casings include the salt content and the quality of processing and packaging.

The HBS published the Dutch translation of the HACCP manual.
All companies have received a copy. This promotes the uniformity of processing world-wide which is an important point for customers and inspectorates.
In the Netherlands, the Food and Consumer Product Safety Authority (VWA) assesses Dutch companies to ensure that the HACCP system is correctly applied.

Microbiological quality
Fresh natural casings always contain micro-organisms. The salting process, which preserves the product, substantially reduces the micro-organic load.

The recommendations on microbiological standards for salted natural casings at reception in the meat products industry are as follows:
  • Control samples should be freed of all residual salt and used without water (shaking off).
  • Control samples should be mixed samples taken from three different packages.

Microbiological values

cfu per gram
fully acceptable
maximum value
total aerobic count
< 1.0 x 105
5.0 x 106
< 1.0 x 102
1.0 x 104
staphylococcus aureus
< 1.0 x 102
1.0 x 103
sulphite-reducing Clostridia
< 1.0 x 102
1.0 x 103
Source: European Natural Sausage Casing Association (ENSCA), November 1996

Chemical composition
Most of the protein in the intestine is collagen. The rest is elastine. The elastine is found in the blood vessels of the intestine. The fat content of salted casings is very low on average. With hog casings, for example, it is less than 2%. Consequently, the potential volumes of fat-soluble residues in natural sausage casings are zero, and cannot be analysed.

Quality issues

Sheep casings are assessed mainly in terms of the presence of holes.
A-quality casings are free of holes.
B-quality casings have few holes, of medium size (3 mm in diameter).
The casings are filled with water or air to determine the quality.
At the same time the diameter is calibrated.
Casings are classified in stages of 2 and 3 mm.
Beef casings range in diameter from 32 mm to 50 mm or more.
Hog casings from 26 mm to 45 mm or more.
Sheep casings from 14 mm to 28 mm or more.
Sometimes, the casings exceed the maximum diameter. They are then categorised as 'extra wide'.

Fringe on the casing ('whiskers')
Casings may have a small fringe of connective tissue. These are the remains of blood vessels in the caul, and show that the caul was not cut away cleanly from the small intestine. Heating removes these 'whiskers'.

Visible fat around veins (veiny tissue)
The veins are the remains of blood vessels. The fat around the veins is clearly visible. This fat disappears when the casings are heated.

Light (thin) spots in the intestinal wall (worm holes)
The light spots arise during cleaning. The show the sites of lymph glands, the 'Peyer plates'. These plates are removed, together wit the mucous membrane. As a result, the tissue is thinner at these points.