Abstract: This study investigated the peptide profiling of four yogurt samples (Youweishu flavored fermented milk, plain flavored fermented milk, Churu 24+K flavored fermented milk and Shitian flavored fermented milk) from local market by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 152, 125, 364 and 274 peptides were identified from the yogurts by LC-MS/MS, respectively. Angiotensin converting enzyme (ACE) inhibitory activity was used to evaluate the biological activities of yogurt peptides. The ACE inhibition rates of peptides from these yogurts were 46.84%, 42.75%, 77.41% and 63.84% at a concentration of 2.0 mg/L, respectively. The large number of identified peptides and high ACE inhibitory activities in Churu 24+K flavor fermented milk may be related to its special ingredients. This study may provide the theoretical basis for further study on the functions and ACE inhibitory activity of yogurt peptides.

Key words: yogurt, peptide profiling, LC-MS/MS, ACE inhibitory activity