| 摘要 |
In the manufacture of artificial sausage casings from fibrous animal material such as skin or muscle tissue by comminuting the material to form a paste or dough and extruding this through annular nozzles, the comminution is carried out while the material is still fresh and has undergone no chemical changes since the slaughter of the animal from which it was obtained, and the material is not treated with any chemicals effecting a degradation of the protein substances of the material before comminution. The material may be kept fresh between slaughter and comminution by refrigeration or storage in vacuum or in an atmosphere not containing oxygen. The material may in addition be subjected to a very moderate degree of drying which does not chemically change the proteins present. The material may be moistened with a little water before comminution, and water may also be added after comminution. Instead of water, glue liquor, liquid extracts from fresh skin material, or liquid containing elastins, keratins or other protein substances in an unmodified form may be added. The comminuted mass may be additionally homogenized before extrusion, and tanning or softening agents, such as glycerine or tricresyl phosphate, may then be incorporated in the mass. The elasticity of the comminuted mass may be adjusted by the addition of chemical swelling agents, the pH value of the mixture indicating its elasticity. A mass having a pH value of 2-5, preferably 3.5, and a dry weight content of 8-10 per cent is particularly suitable for producing extremely thin sausage casings. The elasticity of the paste may be adjusted by mixing the slaughter-fresh material before comminution with old material which has been swollen by chemical agents. Alternatively the old and fresh materials may be comminuted separately before mixing them. The extrusion apparatus need not be equipped with devices for orientating the fibres in several directions.
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