Purification and identification of antioxidant peptides from walnut (Juglans regia L.) protein hydrolysates

► Antioxidant hydrolysates from walnut proteins were prepared using neutrase, alcalase and pepsin. ► Walnut protein hydrolysates were purified sequentially by ultrafiltration, gel filtration and RP-HPLC. ► The activities of peptide were evaluated by radicals scavenging, reducing power and lipid peroxidation inhibitory activity. ► The structure of purified peptide was determined as Ala-Asp-Ala-Phe.