Identification by hydrophilic interaction and reversed-phase liquid chromatography–tandem mass spectrometry of peptides with antioxidant capacity in food residues

• The analytical strategy developed enables the protein extraction from peach by-product.
• Peach seed proteins were hydrolysed with different enzymes.
• Thermolysin yielded the hydrolysate with the highest antioxidant capacity.
• A comprehensive identification of peptides by RPLC- and HILIC-MS/MS was performed.
• Eighteen peptides were identified which contained hydrophobic amino acids.

HILIC- and RP-HPLC-ESI-Q-TOF identification of bioactive peptides with antioxidant capacity in peach by-products was carried out. Peach seeds contain more than 40% of proteins (as dried and defatted basis) and could constitute a cheap source of bioactive peptides. Extracted proteins were digested using four different commercial enzymes. Five assays based on different antioxidant mechanisms were employed for a reliable evaluation of the antioxidant capacity of the extracts. Thermolysin enzyme originated the extract with the most favorable antioxidant capacity. Probably due to a synergic effect among antioxidant peptides, it was not possible to find a peptide fraction with a higher antioxidant capacity than the whole extract. Eighteen peptides were identified in the whole hydrolysate when combining HILIC- and RP-HPLC-ESI-Q-TOF. A high percentage of hydrophobic amino acids were observed within their sequences which is a characteristic feature of the antioxidant nature of peptides.