Discovery of specific antioxidant peptide from Chinese Dahe black pig and hybrid pig dry-cured hams based on peptidomics strategy

The quality of hams obtained from different pig breeds can vary depending on endogenous antioxidant peptides in the hams. The aims of this study were (i) to investigate the specific peptides in Chinese Dahe black pig ham (DWH) and hybrid pig ham (Yorkshire × Landrace × Dahe black ham, YLDWH) and their antioxidant activity, and (ii) to elucidate the relationship between ham quality and antioxidant peptides. iTRAQ quantitative peptidomic method was used to discover specific peptides of DWH and YLDWH. In addition, in vitro assays were performed to evaluate their antioxidant activity. A total of 73 specific peptides were identified from DWH and YLDWH by LC-MS/MS. Forty-four specific peptides in DWH were primarily hydrolysed from myosin and myoglobin by endopeptidases, while 29 specific peptides in YLDWH were primarily hydrolysed from myosin and troponin-T. Six specific peptides that were statistically significantly different based on their fold changes and P-values were selected for the identification of DWH and YLDWH. DWH-derived specific peptide AGAPDERGPGPAAR (AR14), which had high stability and was non-toxic, had the highest DPPH• and ABTS•+ scavenging activity (IC50 = 1.657 mg/mL and 0.173 mg/mL, respectively) and cellular antioxidant capacity. Molecular docking showed that AR14 interacted with Val369, and Val420 of Keap1 via hydrogen bonds. Furthermore, AR14 bound to DPPH and ABTS through hydrogen bonding and hydrophobic interactions. Together, our results demonstrate that the DWH-derived antioxidant peptide AR14 exhibits the free radical scavenging and cellular antioxidant activity and can be used to preserve ham quality and promote human health.