Radical-scavenging activity, ACE-inhibiting capability and identification of rapeseed albumin hydrolysate

Albumin derived from rapeseed was hydrolyzed sequentially using alcalase and flavorzyme to produce antioxidant peptides. To identify antioxidant peptides, rapeseed albumin hydrolysate (RAH) was fractionated using size exclusion chromatography (G-25). The antioxidant activity and angiotensin I-converting enzyme (ACE) inhibiting activity of rapeseed peptides (RSP) purified from RAH were evaluated. The results revealed that RSP-4 had the highest ABTS radical-scavenging activity (TEAC value = 0.24) and ACE-inhibiting capacity (IC50 = 0.19 mg/mL) compared to other fractions. Moreover, RSP-4 was identified as PFDSYFVC (977 D) by electrospray ionization (ESI) mass spectrometry and tandem mass spectrometry (MS/MS).