This study investigated the protective effect of ferulic acid (FA) on the digestibility of oxidized beef myofibrillar protein (MP). MP were treated with varying concentrations of FA (20, 40, and 80 μmol/g pro) and then exposed to oxidation. The results showed that FA inhibited carbonyl in a dose-dependent manner. Fluorescence spectroscopy and molecular docking studies revealed FA was bonded to MP via hydrophobic interactions and hydrogen bonds. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and transmission electron microscope analysis indicated that FA mitigated the aggregation of oxidized MP. Peptidomic analysis showed FA protected 34.24% peptides recover from oxidation loss, and theses recovered peptide were mainly distributed in hydrophobic regions and lysine sites. In vitro digestion showed FA remarkably improved digestibility of oxidized MP (P < 0.05), with 80 μmol/g pro FA mitigating 67.85% loss in digestibility. Overall, FA effectively preserved the release of peptides by inhibiting hydrophobic aggregation and oxidation of lysine residues, thereby alleviating the decrease in digestibility of oxidized MP.

The changes in the sequence and anti-inflammatory properties of bioactive peptides extracted from Xuanwei ham were analyzed after stimulated gastrointestinal digestion in vitro and transport across Caco-2 monolayers. The results showed that the total number of bioactive peptides increased after gastrointestinal digestion, and the proportion of peptides with a molecular mass below 1000 Da in the total number of peptides increased from 40.18% to 57.40%. The inhibitory effect of the peptides on the secretion of inflammatory cytokines in RAW264.7 macrophages was enhanced after simulated digestion. After transport across Caco-2 cells, a total of 24 peptides were detected, including 12 tetrapeptides and 5 tripeptides, of which 62.50% were peptides with a molecular mass less than 500 Da. The synthetic peptides PAG, LVG, LGV and PVL were found to be able to suppress the secretion of NO and tumor necrosis factor α in macrophages. In conclusion, simulated gastrointestinal digestion can change the composition of the peptides from ham and in turn increase the anti-inflammatory activity. In addition, the small peptides transported across Caco-2 cells can inhibit the secretion of inflammatory factors in RAW264.7 macrophages.