Purification and identification of antioxidant peptides from peanut protein isolate hydrolysates using UHR-Q-TOF mass spectrometer

Peanut protein isolate (PPI) was hydrolysed with alcalase to obtain antioxidant peptides. To purify these peptides, the peanut protein isolate hydrolysates (PPIH) were separated by ultrafiltration (MWCO = 3 kDa) and the obtained PPIH-II (Mw < 3 kDa) with higher antioxidant activity was further separated by gel filtration chromatography (Sephadex G-15). After filtration, both peptides, P1 and P4, with stronger antioxidant capacity were fractionated using preparative high performance liquid chromatography (P-HPLC). Three antioxidant peptides were finally purified from P1 and P4 using the UHR-Q-TOF mass spectrometer, and the amino acid sequences of the peptides were identified as Thr-Pro-Ala (286 kDa), Ile/Leu-Pro-Ser (315 kDa) and Ser-Pro (202 kDa), respectively.