Study on some properties of acid-soluble collagens isolated from fish skin and bones of rainbow trout (Onchorhynchus mykiss)

To make more effective use of fish–byproduct resources, acid-soluble collagen (ASC) was isolated from the skin and bones of rainbow trout (Onchorhynchus mykiss) with yields of 9.448% and 1.122% on a wet weight basis, respectively. Based on their electrophoretic pattern, both collagens were classified as type І with slightly different amino acid compositions and low imino acid content. From the result, both collagens were rich in inter- and intra-molecular cross-linked components, β and γ components with bone collagen having more band intensity. Similar changes in viscosity of collagens from the skin and bone of rainbow trout were observed. Collagens from the skin and bones had minimum solubility at pH 9 and 7, respectively. No changes in solubility were observed in the presence of NaCl up to 3% (w/v). However, a sharp decrease in solubility was found above 3% NaCl.