Purification and identification of angiotensin I-converting enzyme inhibitory peptides from fermented walnut residues

Abstract

Defatted walnut residues (DWR) were hydrolysed using Bacillus subtilis to produce angiotensin-I-converting enzyme (ACE) inhibitory peptides. Fermented walnut residue extract (FWRE) was fractionated using ultrafiltration methods to identify the ACE-inhibitory peptides. The fraction with a molecular weight of <1 kDa (WPs-I) presented the greatest ACE-inhibitory activity. Reverse-phase high-performance liquid chromatography was used to separate WPs-I from the most active fractions, and the amino acid sequence of WPs-I was confirmed as VQTL (459.351 Da) and LGYEN (594.276 Da) by UPLC-ESI-MS/MS.