Purification and identification of angiotensin-converting enzyme inhibitory peptides from fermented buffalo milk with Lactobacillus plantarum B

The objective of this study is to ascertain the ACE inhibitory activity of peptides derived from buffalo milk that has undergone fermentation with Lactobacillus plantarum B. A macroporous adsorption resin was also employed to fractionate and purify the peptides. The yield of peptides and the IC₅₀ values for ACE inhibition were evaluated, and the ACE inhibition was also performed under different conditions. The peptide fraction exhibiting a molecular weight below 3 kDa demonstrated the lowest IC₅₀ values and was selected for further analysis. Subsequent analysis revealed that the ACE inhibitory activity of this peptide fraction was more pronounced after ultrafiltration and macroporous adsorption chromatography. The antioxidant capacity of the ACE inhibitory peptides was found to be concentration-dependent. The inhibitory effect of the peptide fraction on ACE was also found to be significantly influenced by variations in temperature, pH, and sodium chloride concentration during the inhibition assay. The sequences of the peptide fraction (MW < 3 kDa) with the strongest ACE inhibition activity were identified by mass spectrometry. Finally, through activity prediction and toxicity evaluation, EMPFPKYP, PFPGPLP, FLPYP and VVPPF were identified as the four peptides with the highest predicted potential activity. The results of this study provide a theoretical and practical basis for the screening and characterization of milk-derived ACE inhibitory peptides.