Department of Chemistry, Ferdowsi University of Mashhad, Mashhad 91779, Iran Gelatin is a protein produced by partial hydrolysis of collagen extracted from the bones, connective tissues, organs, and some intestines of animals such as the domesticated cattle. It has been commonly used as a gelling agent in food, pharmacetutical, and photography. In the present study, gelatin was extracted from the non-treated (Lime- Skin) and treated (Wet Blue Skin) cattle skin. At first, the skins were cutted into the small pieces and incubated in the Ca(OH)2 solution (20 g/ml) for twenty days. Then, the skins were washed with sulfuric acid and deionized water. The final extraction was done with water at different temperatures (55 – 95°C) and the resulting extractions were concentrated. The products were analyzed on the SDS-PAGE, the tanic acid and sulfate copper experiments were also done on the samples by the Aria gelatin factory. The results have been shown that the percentage of the gelatin extracted from the non-treated skin is more than the treated skin. The percentage of the gelatin extracted was decreased by increasing temperature of the extraction in the non-treated skins. On the contrary, the percentage of the gelatin extracted was increased by the elevating the extraction temperature in the treated skins and the maximmum percentage gelatin extraction was at 95°C. The SDS-PAGE analysis have been shown that the pattern of the mobility of the extracted gelatins are the same as the gelatin extracted from the bone by the Aria gelatin factory. The maximmum percentage gelatin extraction was at 55°C from the non-treated skins.

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