Increase in DPPH scavenging ability of proteins from salmon backbones compared to DPPH activity of proteins before hydrolysis as effect of hydrolysis time. Samples: Pr-T: hydrolysis with Protamex (without separation of oil before hydrolysis); C-PP: Coralase PP, Sz: Seabzyme, P-6L: Protex 6L, BrP: Bromelain + Papain mixture, T: Trypsin, C-7089: Coralase 7089, Pr-W: Protamex without addition of water and Pr: Protamex.