Table 2
Summary of isolation strategy for antioxidant peptide obtained from SRH

Isolation step	DPPH radical scavenging activity (%)1)	Isolation fold2)	Protein yield (%)3)
SRH4)	12.84	1	100
Ultrafiltration (< 3 kDa)	23.44	1.83	87.6
Prep-HPLC (Fraction I)	31.72	2.47	47.6
1stRP-HPLC (FractionIV)	41.1	3.2	15.9
2ndRP-HPLC (Isolated peptide)	91.25	7.11	14.8

DPPH radical scavenging activity was tested at a concentration of 1.0 mg/mL.
Isolation fold was calculated as a ratio of the radical scavenging activity of fraction obtained by each step relative to the radical scavenging activity of SRH.
Protein yield was calculated as a percentage of the protein content of fraction obtained by each step relative to the protein content of SRH.
SRH, sandfish roe hydrolysate.