Collagen sausage casings are commonly used since they have certain advantages over natural sausage cas- ings. One of the advantages is that they can be supplied in desired lengths and with a homogeneous cross-section and the desired strength. For a collagen sausage casing to have a uniform and attractive appearance as well, the collagen mass is usually coloured during the manufacture of the sausage casings.

Collagen sausage casings are manufactured by extru- sion of an acid collagen mass, usually obtained from skin splitting, to a continuous tube, which is hardened and, optionally, dried before filling.

The colouring of collagen sausage casings is effect- ed by adding pigments or dyestuffs to the collagen mass before extrusion. Since collagen in its acidified state is sensitive to the effect of pigments or dyestuffs, inorganic as well as organic, first the pigment must be dispersed or the dyestuff must be dissolved to a very weak dispersion/solution, usually with a content of pig- ment and dyestuff, respectively, of 0.5-1% by weight, before the dispersion/solution is slowly added during mixing (homogenisation) of the collagen mass. If the addition takes place too quickly, the collagen unswells or is denaturated, islands of the denaturated collagen and pigment or dyestuff forming in the mass. These islands deteriorate both the extruding properties of the mass and its appearance, which results in a spotted and patchy sausage casing. It is not possible to mix these islands with the mass.

To prevent the formation of such islands, it has until now been necessary to strongly dilute the pigment

dispersion and the dyestuff solution, respectively, and spray it over the collagen mass during mixing.

According to the present invention, a pigment/dye- stuff composition is provided, which in the colouring of collagen sausage casings solves the above-mentioned prob- lems.

The invention relates to a pigment/dyestuff composi- tion for colouring of collagen-containing sausage cas- ings, which comprises 2-10% by weight of pigment/dye- stuff, 3-30% by weight of polyoxyethylene sorbitan fatty acid ester, 1-10% by weight of sorbitan fatty acid ester, 0-70% by weight of dispersing agent, the balance being water and, optionally, other conventional additives.

The invention also relates to the use of such a com- position for colouring of collagen-containing sausage casings.

The combination of polyoxyethylene sorbitan fatty acid ester (so-called polysorbate) and sorbitan fatty acid ester forms with the pigment/dyestuff a stable dis- persion and "encapsulates" the pigment/dyestuff par- ticles, such that they do not come into direct contact with the collagen during mixing with the collagen mass.

As a result, the collagen is protected in its acidified state from being affected by the pigment/dyestuff.

The dispersion of the pigment/dyestuff is improved by using a thicker dispersion. To improve the dispersion, glycerine can therefore be added as dispersing agent (thickening agent).

By using the pigment/dyestuff composition accord- ing to the invention, the pigment/dyestuff can be added quickly and in concentrated form without causing the problems of unswelling/formation of islands. A further advantage of the pigment/dyestuff composition according to the invention is that it is viscous and stable in terms of settling. Moreover, the combination of polysor- bate/sorbitan fatty acid ester results in a more inten- sive colour with the corresponding amount of pigment/dye-

stuff, which implies that the amount of pigment/dyestuff can be reduced to a considerable extent, viz. by about 25%. The use of the pigment/dyestuff composition gives additional positive effects in the form of a more ductile collagen mass with better extruding properties.

The polyoxyethylene sorbitan fatty acid ester is suitably selected from the group consisting of polyoxy- ethylene(20)sorbitan monolaurate, monopalmitate, mono- stearate, tristearate, monooleate, trioleate. The used sorbitan fatty acid ester is suitably selected from the group consisting of sorbitan monolaurate, monopalmitate, monostearate, tristearate, monooleate, trioleate.

The invention will now be described in more detail by way of non-limiting Examples of pigment/dyestuff com- positions.

Example 1 Ingredient % by weight Pigment 8 Polysorbate 80* 7 Sorbitan laurate 1.5 Glycerine 44 Water 39. 5 * Polysorbate 80 = polyoxyethylene(20)sorbitan monooleate Example 2 Ingredient % by weight Pigment 2 Polysorbate 85* 5 Sorbitan trioleate 1 Glycerine 48 Water 44 * Polysorbate 85 = polyoxyethylene(20)sorbitan trioleate

Example 3 Ingredient % by weight Pigment 10 Polysorbate 40* 12 Sorbitan oleate 7.5 Glycerine Water 70.5 * Polysorbate 40 = polyoxyethylene(20)sorbitan monopalmi- tate