## 3 Experimental Section
### Analysis of Antioxidant Activity  
#### 3.3.1 Radical Scavenging Activity  
The scavenging activities of eight isolated peptides (F7-P1 to F7-P8) on HO\(\bullet\), DPPH\(\bullet\), O\({}_{2}^{-}\bullet\), and ABTS\({}^{+}\bullet\) were measured according to previous methods [20; 36]. The results were expressed as a half elimination ratio (EC\({}_{50}\)) defined as the concentration where a sample caused a 50% decrease of the initial radical concentration. The counting method was based on the linear relationship between radical scavenging rates and peptide concentrations [1].  
DPPH\(\bullet\) Scavenging Activity  
Two millilitres of samples consisting of distilled water (DW) and different concentrations of the analytes were placed in cuvettes, and 500 uL of an ethanolic solution of DPPH (0.02%) and 1.0 mL of ethanol were added. A control sample containing the DPPH solution without the sample was also prepared. In the blank, the DPPH solution was substituted with ethanol. The antioxidant activity of the sample was evaluated using the inhibition percentage of the DPPH\(\bullet\) with the following equation:  
\[\text{DPPH}\bullet\text{scavenging activity (\%)}=(\text{A}_{0}+\text{A}^{ \prime}-\text{A})/\text{A}_{0}\times 100\%,\]  
where A is the absorbance rate of the sample, A\({}_{0}\) is the control group absorbance, and A\({}^{\prime}\) is the blank absorbance.  
1.0 mL of a 1.87 mM 1,10-phenanthroline solution and 2.0 mL of the sample were added to a screw-capped tube and mixed. Following this, 1.0 mL of a FeSO\({}_{4}\)7H\({}_{2}\)O solution (1.87 mM) was added to the mixture. The reaction was initiated by adding 1.0 mL of H\({}_{2}\)O\({}_{2}\) (0.03%, v/v). After incubating at 37 \({}^{\circ}\)C for 1.0 h in a water bath, the absorbance of the reaction mixture was measured at 536 nm against a reagent blank. The reaction mixture, without any antioxidant, was used as the negative control, and a mixture without H\({}_{2}\)O\({}_{2}\) was used as the blank. The HO\(\bullet\) scavenging activity (HRSA) was calculated using the following formula:  
\[\text{HRSA (\%)}=[(\text{A}_{\text{s}}-\text{A}_{\text{n}})/(\text{A}_{\text{b}}- \text{A}_{\text{n}})]\times 100\%,\]  
where A\({}_{\text{s}}\), A\({}_{\text{n}}\), and A\({}_{\text{b}}\) are the absorbance values determined at 536 nm of the sample, the negative control, and the blank after the reaction, respectively.  
O\({}_{2}^{-}\bullet\) Scavenging Activity  
Superoxide anions were generated in 1 mL of nitrotetrazolium blue chloride (NBT) (2.52 mM), 1 mL of NADH (624 mM), and 1 mL of different sample concentrations. The reaction was initiated by adding 1 mL of phenazine methosulphate solution (120 uM) to the reaction mixture. The absorbance was measured at 560 nm against the corresponding blank after 5-min incubation at 25 \({}^{\circ}\)C. The scavenging capacity of the O\({}_{2}^{-}\bullet\) was calculated using the following equation:  
\[\text{O}_{2}^{-}\bullet\text{scavenging activity (\%)}=[(\text{A}_{\text{control}}- \text{A}_{\text{sample}})/\text{A}_{\text{control}}]\times 100\%,\]  
where A\({}_{\text{control}}\) is the absorbance without sample and A\({}_{\text{sample}}\) is the absorbance with sample.  
ABTS\({}^{+}\bullet\) was generated by mixing an ABTS stock solution (7 mM) with K\({}_{2}\)S\({}_{2}\)O\({}_{8}\) (2.45 mM). The mixture was left in the dark for 16 h at room temperature. The ABTS\({}^{+}\bullet\) solution was diluted in 5 mM phosphate buffered saline (PBS, pH 7.4) to an absorbance of 0.70 \(\pm\) 0.02 at 734 nm. One millilitre ofdiluted ABTS\({}^{+}\bullet\) solution was mixed with one millilitre of the different sample concentrations. After 10 min, the absorbances at 734 nm were measured against the corresponding blank. The ABTS\({}^{+}\bullet\) scavenging activities of the samples were calculated using the same equation as indicated in O\({}_{2}^{-}\bullet\) scavenging activity (%).