In vitro and in vivo antioxidant activity and umami taste of peptides (< 1 kDa) from porcine bone protein extract

The antioxidant activity in vivo and in vitro of peptides with <1 kDa molecular weight were measured after purification of the enzymatic hydrolysates (FlavourzymeTM and Papain PSM500 together) of porcine bone protein extracts (EH-PBPE). Amino acid sequences of peptides responsible for its characteristic umami taste were identified as Ser-Tyr, Pro-Asn, Gly-Ser, Lys-Pro, and Ala-Pro-His-Arg. The umami compounds were purified using ultrafiltration, gel filtration chromatography, preparative high-performance liquid chromatography, and liquid chromatography-tandem mass spectrometry (LC-MS); and sensory evaluations were done. The in vitro antioxidant activity (as DPPH radical-scavenging activity) of the peptide was 62.9% and umami score (estimated using sensory evaluation) was 8.9 out of 10. Subsequent in vivo studies on antioxidant activities (superoxide dismutase activity and malondialdehyde, glutathione, and protein carbonyl content) of the <1 kDa fraction showed a significant difference from those of the control group, in a dose-dependent manner. In total, 5 peptides were found in the <1 kDa fraction of EH-PBPE using LC-MS. These results suggested that the <1 kDa peptide fraction purified from EH-PBPE might be used as a natural antioxidant to offset oxidative stress.