## 3 Results and Discussion
### Noncellular In Vitro Antioxidant Activity
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Sample Code** & \
\begin{tabular}{l} **ORAC Value** \\ **(\(\upmu\)mol TE/g dw)** \\ \end{tabular} &
\begin{tabular}{l} **FRAP Value** \\ **(\(\upmu\)mol TE/g dw)** \\ \end{tabular} \\ \hline BW-SPH-A & 387.65 \(\pm\) 9.97 \({}^{\text{ab}}\) & 7.41 \(\pm\) 0.15 \({}^{\text{bc}}\) \\ BW-SPH-A-GI & 459.73 \(\pm\) 8.72 \({}^{\text{A*}}\) & 5.60 \(\pm\) 0.03 \({}^{\text{A*}}\) \\ BW-SPH-B & 350.65 \(\pm\) 10.35 \({}^{\text{bc}}\) & 7.25 \(\pm\) 0.22 \({}^{\text{c}}\) \\ BW-SPH-B-GI & 414.20 \(\pm\) 4.68 \({}^{\text{*}}\) & 5.06 \(\pm\) 0.04 \({}^{\text{B*}}\) \\ BW-SPH-C & 330.79 \(\pm\) 9.76 \({}^{\text{c}}\) & 7.67 \(\pm\) 0.14 \({}^{\text{bc}}\) \\ BW-SPH-C-GI & 348.49 \(\pm\) 4.89 \({}^{\text{C}}\) & 4.64 \(\pm\) 0.09 \({}^{\text{C*}}\) \\ BW-SPH-D & 393.32 \(\pm\) 3.32 \({}^{\text{a}}\) & 8.45 \(\pm\) 0.08 \({}^{\text{a}}\) \\ BW-SPH-D-GI & 409.00 \(\pm\) 2.98 \({}^{\text{B*}}\) & 4.75 \(\pm\) 0.06 \({}^{\text{B*}}\) \\ BW-SPH-E & 365.88 \(\pm\) 8.27 \({}^{\text{ab}}\) & 7.57 \(\pm\) 0.10 \({}^{\text{b}}\) \\ BW-SPH-E-GI & 386.50 \(\pm\) 3.23 \({}^{\text{B}}\) & 4.74 \(\pm\) 0.09 \({}^{\text{B*}}\) \\ BW-SPH-F & 345.78 \(\pm\) 4.26 \({}^{\text{c}}\) & 8.03 \(\pm\) 0.23 \({}^{\text{ab}}\) \\ BW-SPH-F-GI & 385.01 \(\pm\) 9.55 \({}^{\text{B*}}\) & 4.48 \(\pm\) 0.08 \({}^{\text{C*}}\) \\ \hline \hline \end{tabular} Values are expressed as mean \(\pm\) SEM of three independent experiments. The samples labelled -GI refer to the samples post-SGID. ORAC: oxygen radical absorbance capacity, FRAP: ferric reducing antioxidant power, TE: Trolox equivalents, dw: dry weight. Different lowercase letters (a,b,c) within a column indicate a significant difference between BWSPHs samples pre-SGID at \(p\) < 0.05. Different capital letters (A,B,C) within a column indicate a significant difference between BWSPHs post-SGID at \(p\) < 0.05. \({}^{\text{*}}\) indicates a significant difference at \(p\) < 0.05 between pre- and post-SGID values.  
\end{table} 
Table 2: In vitro ORAC and FRAP antioxidant activity of blue whiting (_Micromessitis potutassou_) soluble protein hydrolyses (BWSPHs) pre- and post-simulated gastrointestinal digestion (SGID). FRAP values ranging from 7.25 \(\pm\) 0.22 to 8.45 \(\pm\) 0.08 umol TE/g dw were obtained for BWSPHs prior to SGID with BW-SPH-B and BW-SPH-D mediating the lowest and highest activity, respectively (Table 2). The FRAP activity of all samples was significantly decreased following SGID (Table 2). Similar findings were reported for a whey hydrolysate prepared with Alcalase(tm), which demonstrated reduced FRAP and ABTS inhibition and increased ORAC activity post-SGID compared to the undigested Alcalase-hydrolysate (\(p\) < 0.05) [38]. This is not unexpected as the ORAC and FRAP assays are based on different chemical reactions with the ORAC assay measuring the scavenging capacity of test compounds against peroxyl radicals through hydrogen atom transfer (HAT), whereas FRAP is categorized as an electron transfer (ET)-based, nonradical method. Due to the fact that SGID samples demonstrated increased ORAC values but reduced FRAP values compared with the corresponding undigested samples, it is possible that SGID samples scavenge radicals through HAT. The radical scavenging activity of BWSPHs and SGID BWSPHs was also assessed in a cell model (Table 3) which provides a better biological predictor for BWSPHs antioxidant ability. The peptide length and amino acid composition of peptides within the protein hydrolysate, which ultimately influence hydrolysate bioactivity, are dependent on DH. In this case, FRAP results indicate that bioactivity was attenuated during SGID. A correlation between a reduced DPPH scavenging activity and a reducing power of fish protein hydrolysate with increasing DH has been previously observed [39; 40]. The highest activity for both ORAC (459.73 \(\pm\) 8.72 umol TE/g dw) and FRAP (5.60 \(\pm\) 0.03 umol TE/g dw) activity following SGID was observed with sample BW-SPH-A-GI (Table 2).