The method of determination of collagen (hydroxyproline) in squid skin was examined. Results suggest that the determination should be conducted after the raw material was defatted. The hydrolysis of the defatted sample at 120℃ for 12h or at 130℃ for 6h was equal to that at 105℃ for 16h as recommended by ISO. For the purpose of recovering collagen from squid skin, the grounded material was treated with hot water and proteases and the recovery rate of collagen was compared. The treatments with pepsin ( 5℃,pH2...