In vitro bioaccessibility and antioxidant properties of unicorn leatherjacket fish (Aluterus monoceros) skin collagen peptides prepared using crude collagenase enzyme isolated from fish fins

In this study unicorn leatherjacket (Aluterus monoceros) fish skin collagen was hydrolyzed with the crude collagenase extracted from the fish fins discarded as by-product at three different temperature viz. 50C (CP-5), 250C (CP-25) and 500C (CP-50) to obtain collagen peptide of three molecular mass fraction viz., <30kDa, <10kDa and <3kDa by ultra-filtration using TFF system. The collagenase extracted from fins had a MW of 29kDa and hydrolyzed skin collagen to molecular masses <24kDa efficiently with a DH ranging from 6.6-7.6%. CP-5 peptides with <3kDa showed the maximum antioxidant activity. DPPH and hydroxy radical scavenging activities were good with 70% and 68%, while metal chelating ability was 33% and reducing power was 0.3315. In vitro gastro-intestinal digestion study indicated that after pepsin digestion protein was more in CP-5 than CP-25 and CP-50. The rate of peptide absorption of the CP was significantly high in <3kDa CP-5 (32.56%), followed by CP-25 (32.43%) and CP-50 (32.35%) after gastric and pancreatin digestion. CP-5 of <3kDa having better antioxidative activities of collagen peptides in in vitro gastro-intestinal digests than CP-50 of <3kDa. The study thus indicated that CP with good antioxidant activity shall be produced by hydrolysis the skin at 50C, rather than at 500C.