Collagen from jumbo squid fin: Extracting conditions and influence of the protease system on collagen hydrolysate antioxidant activity

The optimal alkaline and acid conditions for insoluble collagen extraction from jumbo squid fin (JSF) were established by factorial analysis. Dependent variable: protein concentration; independent variables: NaOH and HCl concentrations. The antioxidant properties of JSF collagen hydrolysates obtained by two protease systems were studied. Moreover, jumbo squid skin (JSS) collagen was obtained and hydrolysated under optimal conditions. The optimal extraction condition was 0.5 M NaOH followed by 0.2 M HCl. Collagen α-chains were detected in both JSF and JSS. Collagen β-component was detected only in JSS. JSS collagen showed higher levels of polar and hydrophobic amino acids. The JSF hydrolysates produced by subtilisin showed a lower degree of hydrolysis and higher antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), and oxygen radical absorbance capacity-fluorescein (ORACFL)) than those produced by a mixture of trypsin, chymotrypsin, and peptidase. The JSS hydrolysates showed a higher antioxidant capacity. We have thus established a suitable process to improve the utility of JSF.