Evaluation of methods of extraction of collagen and its chemical properties [Philippines]

Among the extraction methods studied, Vognarova method yielded the highest collagen content, followed by commercial extraction and then Neuman method, Hill method and acid extraction methods. The collagen content of pig skin obtained by acid extraction was 4.5 mg hydroxyproline 15 g fresh weight of sample (equal to 1.6 g collagen)/100 g protein which was lower compared to the data obtained by Klein et al (1969) (7 mg hydroxyproline/5 g fresh weight of sample). In the Bognarova extraction method the collagen content obtained in pig, beef, goat and buffalo skins were 15.5 g, 8.5 g, 9.6 g and 0.6 g/100 g protein, respectively. The collagen solubilized by commercial extraction method in pig, beef, goat and buffalo skins were 48.7 g, 55.2 g, 52.6 g and 56.3 g/100 g protein, respectively. The coll1892agen solubilized by commercial extraction method in pig, beef, goat and buffalo skins were 32.8 g, 30.5 g, 17.8 g and 9.1 g/100 g protein, respectively. In the food grade collagen extraction method the collagen content obtained in pig, beef, goat and buffalo skins were 15.5 g, 8.5 g, 9.6 g and 0.6 g/100 g protein, respectively. The collagen solubilized by commercial extraction method in pig, beef, goat and buffalo skins were 42.1 g, 48.9 g, 51.6 g and 49.1 g/100 g protein, respectively. Meanwhile, the collagen obtained by Neuman extraction method in pig, beef, goat and buffalo skins were 15.5 g, 8.5 g, 9.6 g and 0.6 g/100 g protein, respectively. The collagen solubilized by commercial extraction method in pig, beef, goat and buffalo skins were 21.0 g, 38.1 g, 27.3 g and 31.1 g/100 g protein, respectively. Glycine content was the highest among the amino acids found in pig skin collagen (23.46%), beef skin collagen (25.83%), goat skin collagen (17.43%) and buffalo skin collagen (19.77%). All of the animal skin collagen studied, showed that glycine, proline, hydroxyproline, glutamic acid and alamine were the predominant amino acids present. Animal skin collagen had no cystine res