## 3 Results and Discussion
### Release of Free Amino Acids Contributing to Antioxidant Activity  
The release of FAAs from frozen samples correlated positively with the FRAP activity (\(p<0.05\)) (Figure 11). Glutamine glycine/arginine and valine showed a positive correlation with the FRAP activity. The ABTS activity also correlated positively with the released FAAs through the digestive process (\(p<0.05\)). Glycine/arginine, histidine, methionine, and serine showed a highly positive correlation, and lysine, threonine, and valine showed a moderately positive correlation with the ABTS activity. Glutamine was found to have a moderately positive correlation (\(p<0.05\)) with the ORAC activity. The FAAs showed a moderate positively correlation with ABTS (\(p<0.05\)) through the digestive process. Figure 10: The oxygen radical absorbance capacity (ORAC) activity of the simulated gastrointestinal digestion in frozen (\(n=10\)) and freeze-dried (\(n=5\)) red sea cucumber (_Parastichopus tremulus_). The frozen samples have theoretically been calculated from wet weight to dry weight. The results are presented as mean \(\pm\) standard error in mmol Trolox equivalents/100 g dry weight sea cucumber. \({}^{*}\) Denotes significant differences (\(p<0.05\)) between frozen and freeze-dried samples at the specific time point. a, b, c, x, and y denote significant differences (\(p<0.05\)) in frozen (x, y) or freeze-dried (a–c) samples through the digestive process. The release of FAAs from freeze-dried samples correlated both positively and negatively with the FRAP activity (\(p<0.05\)) (Figure 12). Glutamine, lysine, and threonine showed a highly positive correlation, and asparagine, isoleucine, leucine, methionine, and phenylalanine showed moderate positive correlation with the FRAP activity. However, aspartic acid showed a highly negative correlation with the FRAP activity. The ABTS activity also correlated both positively and negatively with the released FAAs through the digestive process (\(p<0.05\)). Glutamine, lysine, and threonine were found to have a highly positive correlation, and asparagine, leucine, methionine, and phenylalanine were found to have moderately positive correlation with the ABTS activity. However, aspartic acid was found to have a highly negative correlation with ABTS activity. At last, ORAC activity correlated both positively and negatively with the released FAAs through the digestive process (\(p<0.05\)). Lysine showed a low positive correlation, glutamine, and phenylalanine showed a moderately positive correlation, and leucine, methionine and threonine showed a highly positive correlation with ORAC activity. However, alanine showed a moderately negative correlation, aspartic acid, and glycine/arginine showed a highly negative correlation with the ORAC activity. Figure 11: The Pearson correlation in the released free amino acids (FAAs) during the simulated gastrointestinal digestion of frozen red sea cucumber (_Paustichopus tremulus_) (\(n=10\)), and between ferric reducing antioxidant power (FRAP), 2*-azino-bis-(3-ethylbenzothazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC). The correlation range between 0.00 to \(\pm 0.10\) denotes markedly low and negligible correlation, while a range from \(\pm 0.10\) to \(\pm 0.30\) denotes very low correlation, \(\pm 0.30\) to \(\pm 0.50\) denotes low positive correlation, \(\pm 0.50\) to \(\pm 0.70\) denotes moderate correlation, \(\pm 0.70\) to \(\pm 0.90\) denotes high correlation, \(\pm 0.90\) to \(\pm 0.99\) denotes very high correlation, and 1.00 denotes perfect correlation. * Denotes statistically significant differences (\(p<0.05\)), calculated by ANOVA. The antioxidant activity is dependent on the amino acid sequence, the structure of the peptides, and the availability and the amount of hydrophobic amino acids in the peptides [70].