The in vitro antioxidant properties of alcalase hydrolysate prepared from silkie fowl (Gallus gallus) blood protein

Two types of proteins including blood plasma protein and blood cell protein were isolated from silkie fowl (Gallus gallus) blood and hydrolyzed using alcalase for 0, 2, 4 and 6 h. The blood plasma protein hydrolysate (BPH) and blood cell protein hydrolysate (BCH) were analyzed for pH value, peptide content and antioxidative properties. The significantly higher peptide contents were observed in BPH than that of BCH, which showed that blood plasma protein was more suitable to hydrolysis by alcalase than blood cell protein. Both BPH and BCH showed strong 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical‐scavenging activity and Fe2+ chelating ability. BPH at 4 h of hydrolysis (BPH4) demonstrated significantly higher antioxidant capacity than those treated by alcalase in most of the assays. The BPH4 was separated using ultra‐filtration and assessment of the fractions and indicated that low molecular weight of peptides (