| 摘要 |
1,139,233. Tubular films. TEE-PAK Inc. 29 April, 1966 [13 July, 1965], No. 19008/66. Heading B5B. A method of preparing an edible tubular collagen casing comprises treating a fresh or frozen or salt-cured animal hide with a limecontaining solution for a time, in the range 3-12 hours, sufficient to at least partially dehair the hide without degrading the collagen, washing the hide to remove excess liming solution, removing the epidermal layer and remaining hair, grinding the limed hide at a temperature less than 20‹ C. to produce a slurry of finely divided collagen in water, treating the slurry with acid at a pH of 2À5 to 3À7 to swell the collagen and burst the fibre bundles to form fibrils, the washing, grinding, and acidification of the hide being carried out in less than 12 hours, extruding the slurry having a solid collagen content of 2-6% by weight through an annular die to form a collagen tube, immersing the tube in a coagulating bath, tanning the collagen tube, and washing, plasticizing, and drying the tube to produce a translucent non-fibrous edible product. In a preferred method, the epidermal layer and remaining hair are removed mechanically and the hide is then de-fleshed and cut into pieces prior to grinding, and the acid-treated slurry is homogenized, filtered and de-aerated prior to extrusion. The slurry preferably contains 3À5 to 5% collagen. The lime solution is preferably a solution containing excess solid lime, sodium sulfhydrate (NaSH), and dimethylamine sulphate. The coagulating bath suitably contains an alkali metal sulphate or ammonium sulphate. In examples: (1) a coagulating bath consisting of 42% ammonium sulphate in water is used; (2) a coagulating bath consisting of 35% aqueous ammonium sulphate is used; (3) 30% aqueous ammonium sulphate. The tanning bath suitably contains a tanning agent comprising a soluble ferric or aluminium salt or a non-toxic dialdehyde. In examples: (1) a tanning bath comprising an aqueous solution of 10% ferric ammonium sulphate and 20% ammonium sulphate is used; (2) the tanning bath comprises 3% aqueous solution of glutaraldehyde at pH 5À0; (3) a conventional alum tanning bath is used. In general, plasticization is effected with an aqueous solution of glycerol. Drying is effected in warm air. In Fig. 2, the collagen slurry is introduced through inlet conduit 1 into die 2 having an annular die outlet 3 through which casing 4 is extruded. Die 2 has an inner tube 5 which extends upwardly within the extruded casing to remove coagulating bath from therewithin. Die 2 is located at the bottom of container 6 containing coagulating bath 7, which circulates through conduit 8 from tube 5 for removal of the coagulating bath from inside the extruded casing. Casing 4 which is coagulated in bath 7 passes over a series of rollers (not shown) and is directed successively through tanning, wash and plasticizing baths, hence to wind up on a reel, or alternatively to a shirring machine. |
