Effects of simulated gastrointestinal digestion on protein degradation and bioactive peptides in Monascus cheese: a peptidomics and bioinformatics study

Abstract

This study investigated the effects of simulated gastrointestinal digestion on protein degradation and bioactivity in Monascus cheese during its optimal ripening period. By integrating peptidomics and bioinformatics approaches, we comprehensively analyzed changes in peptide profiles and identified potential bioactive peptides before and after digestion. Following simulated gastrointestinal digestion, macromolecular proteins in Monascus cheese underwent further hydrolysis, yielding low-molecular-weight peptides and free amino acids. Significant alterations in peptide profiles were observed, accompanied by marked increases (P < 0.05) in ACE-inhibitory activity, hypoglycemic activity, and DPPH free radical scavenging capacity. A total of 2631 milk protein-derived peptides were identified across different digestion stages, including 69 putative angiotensin-converting enzyme (ACE) inhibitory peptides, 32 antioxidant peptides, 21 dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides, and 44 antimicrobial peptides. Notably, the ACE inhibitory peptides NLHLPLPLL, GPFPIIV, and VENLHLPLPLL exhibited the highest peak intensities, all exceeding 10⁹. Molecular docking analysis demonstrated that these peptides possessed low binding free energies (ranging from −5.84 to −6.76 kcal/mol) and consistently interacted with key residues in the ACE active pocket. Molecular dynamics (MD) simulation validated the stability of the complexes. These findings provide critical insights into the functional properties of Monascus cheese and the bioavailability of its bioactive peptides, offering both a theoretical foundation and functional data to support the future industrial-scale production of Monascus cheese.