Antioxidant and Cryoprotective Effects of Bone Hydrolysates from Bighead Carp (Aristichthys nobilis) in Freeze-Thawed Fish Fillets

Bone hydrolysates from bighead carp (Aristichthys nobilis) were prepared using Protamex and Alcalase with degrees of hydrolysis (DH) of 5%, 10% and 15%. The antioxidant activity of bone hydrolysates was evaluated in vitro and then the hydrolysates with better antioxidant activity were used to immerse bighead carp fillets through a vacuum impregnation process at concentrations of 1% and 2%. Among the six hydrolysates, fish bone hydrolyzed with Protamex at DH 10% exhibited the highest ability to scavenge 1, 1-diphenyl-2-picrylhydrazyl (DPPH) (88.79%), 2, 2 '-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) (57.76%) and hydroxyl radicals (62.72%), as well as to chelate ferrous ions (91.46%). The hydrolysates effectively postponed freezing- and thawing-induced protein/lipid oxidation. Compared with the fillets without treatment, the impregnated fillets had higher sulfhydryl contents, greater Ca2+-ATPase activity, lower carbonyls and lower thiobarbituric acid-reactive substances (TBARS). Bone hydrolysates also have a positive effect on the texture and water-holding ability of freeze-thawed fish fillets. Fish bone hydrolysates of Protamex could serve as potential antioxidants to preserve fish fillets.

Automated summary

Bone hydrolysates from bighead carp prepared with Protamex exhibited strong antioxidant activity, effectively delaying protein and lipid oxidation. Impregnating carp fillets with these hydrolysates improved sulfhydryl content, Ca2+-ATPase activity, and reduced carbonyls and TBARS levels. Overall, Protamex-derived fish bone hydrolysates have potential as antioxidants for fish fillet preservation.