Enzymes-dependent antioxidant activity of sweet apricot kernel protein hydrolysates

The bioactive peptides derived from sweet apricot kernel residue after oil extraction exhibit different bioactivities, but their structure-activity relationships have not yet been established. In this research, the antioxidant activities (hydroxyl, superoxide anion, DPPH radical scavenging capacity and iron-binding ability) of sweet apricot kernel protein hydrolysates (SAKPHs) obtained by different enzymes at the temperature range (37-70 degrees C) were evaluated. The amino acid sequences of the hydrolysates by different enzymes were identified by LC-ESIMS/MS. The results showed that five novel antioxidant peptides with Lysine at the C-terminal end were found in the Neutrase' SAKPHs. Two peptides with Serine-terminal end in the Alcalase' SAKPHs and with N-terminal end in the Papain' SAKPHs were obtained respectively. Three atypical peptides were detected in the Flavourzyme' SAKPHs. The SAKPHs by the Alcalase (SAKPHs-A) at 50 degrees C had highest degree of hydrolysis and a relatively smaller molecular weight distribution compared with the other three proteases, and presented the higher antioxidant activity. The N-terminal peptide SHNLPILR containing a side chain combination of aspartic acid and histidine contributes to the stronger antioxidant activities of SAKPHs-A. This research supplies a guideline for functional peptides released from dietary proteins by the utilization of specific enzymes in the food industry.