Antioxidant activity of protein hydrolysates and purified peptides from Zizyphus jujuba fruits

► Antioxidant activity of Zizyphus jujuba -derived protein hydrolysates were evaluated. ► To purify antioxidant peptides, trypsin hydrolysate was fractionated using RP-HPLC. ► The most potent peptides, named F3 and F6, were identified to be VGQHTR and GWLK. ► EC50 values of the F3 and F6 peptides were 0.6 and 0.5 mg/ml using DPPH assay. ► These peptides had 50% chelating effect on ferrous ion at 1.18 and 0.86 mg/ml.