Gelatin from soluble collagen

Fig. 23. Specific rotation of ichthyocol collagen and gelatin at 313 wn as a function of temperature. Collagen concentration = 1.14 mg/ml, gelatin concentration = 1.67 mg/ml. T, gelatin, after 24 hr at 3°C A, gelatin after 6 days at 3°C O, gelatin after 28 days at 3°C O, native soluble collagen. (From Harrington and von Hippel, 1961.)...

Collagens from various sources can be dispersed in differing degrees. Leplat (136) examined different animal tendons, emplo3dng formic, propionic, citric and even hydrochloric acids for their partial solution. Faur Fremiet and Baudouy (71) found ichthyocol completely soluble in 0.0004 N formic acid and formamide, the latter also dispersing mammalian tendons partially. Salo (184) has reported molecular shapes and sizes, similar to those of Scatchard et al. for parent gelatin, from viscosity studies of ichthyocol dispersed in warm dilute acetic acid solutions containing some salt. 

Materials. Soluble collagen [ type I (70%) + type III (30%) ] was obtained from pig skin by HCl extraction. Gelatin (t e 1) which was extract from bovine bone by alkaline process was supplied by Nitta Gelatin Co. Ltd, Osaka, Japan and used as received. The average molecular weight of gelatin was about 100,000. 

The denaturation phenomenon is the basis for a simple test for the identification of native soluble collagen in cosmetic raw materials from a homogeneous collagen solution, insoluble collagen fibrils can be obtained if sodium chloride is added to the solution to a final concentration of 5-7%. Fibrils from native collagen but not gelatinized or hydrolyzed collagen will be precipitated. 

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