Isolation and characterisation of collagens from the skin, scale and bone of deep-sea redfish (Sebastes mentella)

To make more effective use of underutilised resources, collagens from skin, scale and bone (SKC, SCC and BOC) of deep-sea redfish were isolated with acetic acid and characterised for their potential in commercial applications. The abundant ash and fat in the materials could be removed effectively by EDTA and hexane treatment in 24 h, with high recoveries of protein. The yield of SKC (47.5%) was significantly higher than that of SCC and BOC (6.8% and 10.3%, respectively). The denaturation temperatures of SKC, SCC and BOC were 16.1 °C, 17.7 °C and 17.5 °C, respectively, which were lower than those of most other fish species. The amino acid profiles of these collagens were similar with a low imino acid content, which might be the reason for the low denaturation temperature. All the collagens were type I mainly and maintained their triple helical structures well with slight molecular structure differences. SKC possessed a higher degree of intermolecular cross-linking and molecular order, but the extent of peptide chain unwinding was also higher, due to the existence of fewer hydrogen bonds, compared to SCC and BOC.