Effect of processing conditions on functional properties of collagen powder from skate ( Raja kenojei ) skins

Optimum conditions for collagen extraction from skate ( Raja kenojei ) skins with various liming concentrations, extraction solution pH, extraction temperature and time, and functional properties were investigated. The optimum conditions for collagen extraction are as combination of place the skins in a lime solution of 0.15 N of NaOH, extract with 5 volumes water (pH 4.0) for 4 hr at 40°C, filter, centrifuge, and lyophilize to obtain collagen powder. The characteristics of skate skin collagen obtained under optimum extraction conditions were: solubility 82.7%, turbidity 0.28, and Hunter color L, a , and b values were 88.4, 0.92, and 11.2, respectively. On the other hand, the acidic pH values (3.0 and 5.0) of collagen were more resistant to precipitation upon extended heating.