Angiotensin-converting enzyme inhibitory peptides from goats' milk released by in vitro gastro-intestinal digestion

The aim of this study was to identify the angiotensin-converting enzyme (ACE) inhibitory peptides released after in vitro gastro-intestinal digestion of skimmed goats' milk. The experimental approach involved a recently developed harmonised static in vitro digestion model, with mass spectrometry (MS) to identify bioactive peptides. Peptides in the post-pancreatic digest were extracted by ultrafiltration and isolated by reversed-phase high-performance liquid chromatography followed by MS. Among the identified sequences, eighteen were identical to known bioactive peptides with ACE-inhibitory activity. Peptides with dipeptidyl peptidase IV-inhibitory and antioxidant activities were also identified. The antihypertensive tripeptides valine-proline-proline and isoleucine-proline-proline were released from goats’ milk protein during in vitro gastro-intestinal digestion at concentrations of 1829.8 ± 216.4 and 141.4 ± 15.1 ug L-1, respectively. This research underlines the suitability of the harmonised digestive model system to study the release of short bioactive peptides during gastro-intestinal transit.