Physicochemical and functional properties of gelatin from the skin of unicorn leatherjacket (Aluterus monoceros) as affected by extraction conditions

•Extraction condition affected properties of gelatin from unicorn leatherjacket skin.•Yield increased but gel strength decreased with increasing temperature and time.•Interfacial properties of gelatin varied with extraction conditions.

Physicochemical and functional properties of gelatin from the skin of unicorn leatherjacket extracted at different temperatures for various times were determined. Yield, recovery and free amino group content of gelatin increased, but gel strength generally decreased as the extraction temperature and time increased (P < 0.05). All gelatins contained α1 and α2 chains as the predominant components. FTIR spectra of all gelatins showed a significant loss of the triple-helix. Gels of gelatin extracted at higher temperature for longer time had larger strands with larger voids. At the same level of gelatin, emulsifying and foaming properties varied with extraction conditions. Emulsion activity index (EAI) of all gelatins decreased with increasing concentrations (P < 0.05). Nevertheless, the highest emulsion stability index (ESI) was observed at a level of 3% (P < 0.05). Foam expansion (FE) and foam stability (FS) of gelatin generally increased as the concentration increased (P < 0.05).