Antioxidant properties of carp (Cyprinus carpio L.) protein ex vivo and in vitro hydrolysates

•The antioxidant activity of carp muscle protein hydrolysates was examined.•Antioxidant peptides were found in carp muscle protein hydrolysates.•Ex vivo and in vitro hydrolysates of carp muscle proteins differ in antioxidant activity. The presence of specific peptides with antioxidant properties released during carp protein ex vivo and in vitro hydrolysis by human/porcine digestive enzymes, respectively, was examined. Based on the results of the in silico data analysis, antioxidant peptides were selected for subsequent identification in the digests/hydrolysates. Carp proteins were more resistant to hydrolysis by porcine enzymes than by human digestive juices. The sarcoplasmic proteins were hydrolyzed faster than the myofibrillar ones by both human/porcine enzymes. The in vitro myofibrillar protein hydrolysate showed the highest ABTS+ scavenging activity (∼232.3 TEAC, μM Trolox/g), whereas the ex vivo hydrolysate of sarcoplasmic proteins showed the highest DPPH scavenging activity (∼88μM/g) and reducing power. Five antioxidant peptides were identified in carp protein ex vivo and in vitro hydrolysates: FIKK, HL, IY, PW, VY. The peptide HL from myofibrillar proteins was identified only in the ex vivo hydrolysate, whereas the peptide PW from sarcoplasmic proteins was identified only in the in vitro hydrolysate.