Process for the preparation of a collagen product for medical and cosmetic purposes

Claim 1

In a process for the preparation of collagen products for medical and cosmetic purposes comprising the steps of finely comminuting collagen-containing animal tissues at temperatures not exceeding 40° C., degreasing the resulting tissue pulp and simultaneously removing therefrom undesireable water-soluble non-collagen type ballast substances by repeatedly treating the said tissue pulp with about a five-fold volume, based on the pulp volume, of a 5 to 15% aqueous sodium chloride solution containing about 0.2 to 1 part by weight of sodium azide as a preserving agent per 1000 parts by weight of the said solution and 0.5 to 2% by weight of a non-ionic fat-dispersing wetting agent, washing the resulting fiber pulp with water or 0.1 to 0.5% aqueous formic, acetic or citric acid, digesting the fiber pulp for 8 to 48 hours at a pH of about 2.5 to 3.5 in a five-fold volume, based on the volume of the pulp, of 0.1 to b 5% aqueous acetic acid containing about 1 part by weight of pepsin per 1000 parts by weight of the tissue used as the starting material in order to remove non-collagen type proteins and telopeptides, precipitating collagen from the resulting collagen suspension by the addition thereto of aqueous sodium chloride in such a quantity that the sodium chloride concentration of the suspension is about 3 to 5%, separating the precipitated collagen and substantially desalting it by ultrafiltration, dialysis or washing with 60 to 75% aqueous ethyl alcohol so that the collagen concentration in the desalted solution is about 1%, dissolving the desalted collagen in demineralized or distilled water containing up to 3% by weight of a volatile strong organic acid in such a proportion that the concentration of collagen in the resulting solution corresponds to a dry residue of about 0.5 to 2% by weight, freeze-drying the collagen solution, and sterilizing the freeze-dried collagen product, the improvement comprising: subjecting the collagen product to a heat treatment or a treatment with gaseous hydrogen halide after freeze-drying, before or after sterilization, for a time sufficient to impart increased absorption and wet strength to the collagen product.