Hydrolysates of Fish Skin Collagen: An Opportunity for Valorizing Fish Industry Byproducts

Abstract

During fish processing operations, such as skinning and filleting, the removal of collagen-containing materials can account for up to 30% of the total fish byproducts. Collagen is the main structural protein in skin, representing up to 70% of dry weight depending on the species, age and season. It has a wide range of applications including cosmetic, pharmaceutical, food industry, and medical. In the present work, collagen was obtained by pepsin extraction from the skin of two species of teleost and two species of chondrychtyes with yields varying between 14.16% and 61.17%. The storage conditions of the skins appear to influence these collagen extractions yields. Pepsin soluble collagen (PSC) was enzymatically hydrolyzed and the resultant hydrolysates were ultrafiltrated and characterized. Electrophoretic patterns showed the typical composition of type I collagen, with denaturation temperatures ranged between 23 °C and 33 °C. In terms of antioxidant capacity, results revealed significant intraspecific differences between hydrolysates, retentate, and permeate fractions when using β-Carotene and DPPH methods and also showed interspecies differences between those fractions when using DPPH and ABTS methods. Under controlled conditions, PSC hydrolysates from Prionace glauca, Scyliorhinus canicula, Xiphias gladius, and Thunnus albacares provide a valuable source of peptides with antioxidant capacities constituting a feasible way to efficiently upgrade fish skin biomass.

Keywords: ABTS; DPPH; antioxidant activity; collagen; enzymatic hydrolysis; β-carotene.

Figure 1

7% Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) showing Pepsin soluble collagen (PSC) from Prionace glauca (PGLA), Scyliorhinus canicula (SCAN), Thunnus albacares (TALB) and Xiphias gladius (XGLA). M.W: Molecular Weight Standards. Col I: standard collagen type I from mammal.

Figure 2

Intraspecific differences between hydrolysate (H), retentate (R) and permeate (P) in XGLA analyzed by DPPH method and in TALB analyzed by β-Carotene method. Different letters indicate significant differences among means (p ≤ 0.05).

Figure 3

Interspecies differences in hydrolysate fraction using ABTS (A); in retentate fraction using DPPH (B) and ABTS (C); in permeate fraction using ABTS (D). Different letters indicate significant differences among means (p ≤ 0.05).

Figure 4

Scheme for the recovery of pepsin soluble collagen (PSC), preparation of the hydrolysate and analytical determinations.