Structural and functional properties of collagen isolated from lumpfish and starfish using isoelectric precipitation vs salting out

•Collagen was extracted from starfish and lumpfish by a resource smart approach.•Resource demanding salting-out was replaced by isoelectric precipitation.•Mass yield and recovery increased by applying isoelectric precipitation.•Isoelectric precipitation had least effect on structural and functional properties. The possibility of replacing the very time and resource demanding salting out (SO) method with isoelectric precipitation (IP) during collagen extraction from common starfish and lumpfish was investigated. The effect of IP on yield, structural and functional properties of the collagens was therefore compared with SO. Application of IP resulted in a higher or similar collagen mass yield compared with SO from starfish and lumpfish, respectively. However, the purity of collagens recovered with IP was lower than those recovered with SO. Replacing SO with IP did not affect polypeptide pattern and tropohelical structural integrity of collagen from the two resources as revealed with SDS-PAGE and FTIR analysis. Thermal stability and fibril formation capacity of collagens recovered with IP were also well preserved. Overall, the results showed that the IP can be a promising resource smart alternative for the classic SO precipitation during collagen extraction from marine resources.