Angiotensin-converting enzyme inhibitory activity of peptides derived from caprine kefir

In this study, a potent angiotensin-converting enzyme (ACE)-inhibitory activity was found in a commercial kefir made from caprine milk. The low molecular mass peptides released from caseins during fermentation were mainly responsible for this activity. Sixteen peptides were identified by HPLC-tandem mass spectrometry. Two of these peptides, with sequences PYVRYL and LVYPFTGPIPN, showed potent ACE-inhibitory properties. The impact of gastrointestinal digestion on ACE-inhibitory activity of kefir peptides was also evaluated. Some of these peptides were resistant to the incubation with pepsin followed by hydrolysis with Corolase PP. The ACE-inhibitory activity after simulated digestion was similar to or slightly lower than unhydrolyzed peptides, except for peptide β-casein f(47-52) (DKIHPF), which exhibited an activity 8 times greater after hydrolysis.This work has received financial support from projects AGL 2001-1261 and AGL2004-06903-C02-01. The authors acknowledge Röhm Enzyme Gmbh for providing the Corolase PP enzyme preparation. A. Quirós was the recipient of a fellowship of the I3P Programme from the Consejo Superior de Investigaciones Científicas. B. Hernández-Ledesma was the recipient of a fellowship from Instituto Danone