## 3 Results and Discussion
### Amino Acid and Peptide Profile
#### 3.2.1 Amino Acids
These amino acids were also high in HYDR2, which  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Essential** & **CONC1** & **CONC2** & **CONC3** & **HYDR1** & **HYDR2** & **COLL1** & **[41]** \\ \hline His & \(23.8\pm 3.33\,^{\text{a}}\) & \(23.4\pm 3.28\,^{\text{a}}\) & \(19.6\pm 2.75\,^{\text{a}}\) & \(18.7\pm 2.62\,^{\text{a}}\) & \(23\pm 3.22\,^{\text{a}}\) & \(7.6\pm 1.06\,^{\text{b}}\) & 15 \\ [PERSON] & \(47.6\pm 6.67\,^{\text{a}}\) & \(46.5\pm 6.51\,^{\text{a}}\) & \(38.1\pm 5.34\,^{\text{ab}}\) & \(40.8\pm 5.70\,^{\text{ab}}\) & \(32.5\pm 4.54\,^{\text{b}}\) & \(16.4\pm 2.30\,^{\text{c}}\) & 30 \\ [PERSON] & \(83.0\pm 11.62\,^{\text{a}}\) & \(81.8\pm 11.46\,^{\text{a}}\) & \(69.6\pm 9.74\,^{\text{a}}\) & \(76.2\pm 10.67\,^{\text{a}}\) & \(57.3\pm 8.02\,^{\text{a}}\) & \(32.6\pm 4.57\,^{\text{b}}\) & 59 \\ [PERSON] & \(83.8\pm 11.73\,^{\text{a}}\) & \(87.3\pm 12.23\,^{\text{a}}\) & \(75.1\pm 10.52\,^{\text{a}}\) & \(85.9\pm 12.02\,^{\text{a}}\) & \(81.2\pm 11.36\,^{\text{a}}\) & \(50.5\pm 7.06\,^{\text{b}}\) & 45 \\ Met & \(32.4\pm 4.54\,^{\text{a}}\) & \(32.8\pm 4.59\,^{\text{a}}\) & \(28.5\pm 4.00\,^{\text{ab}}\) & \(26.3\pm 36.4\,^{\text{a}}\) & \(26.8\pm 3.75\,^{\text{a}}\) & \(14.6\pm 2.04\,^{\text{b}}\) & 22 \({}^{1}\) \\ Phe & \(22.8\pm 6.22\,^{\text{a}}\) & \(43.3\pm 6.06\,^{\text{a}}\) & \(36.6\pm 5.12\,^{\text{a}}\) & \(37.9\pm 5.31\,^{\text{a}}\) & \(31.7\pm 4.43\,^{\text{ab}}\) & \(23.0\pm 3.21\,^{\text{b}}\) & 38 \({}^{2}\) \\ Thr & \(50.5\pm 7.06\,^{\text{a}}\) & \(47.9\pm 6.71\,^{\text{a}}\) & \(41.2\pm 5.77\,^{\text{ab}}\) & \(41.7\pm 5.84\,^{\text{ab}}\) & \(43.8\pm 6.14\,^{\text{ab}}\) & \(30.9\pm 4.33\,^{\text{b}}\) & 23 \\ Trp & \(12\pm 1.21\,^{\text{a}}\) & \(11.7\pm 1.17\,^{\text{a}}\) & \(9.2\pm 0.92\,^{\text{b}}\) & \(7.6\pm 0.76\,^{\text{b}}\) & \(5\pm 0.49\,^{\text{c}}\) & \(<0.01\,^{\text{d}}\) & 6 \\ Val & \(28.5\pm 7.67\,^{\text{a}}\) & \(53.4\pm 7.48\,^{\text{a}}\) & \(44.9\pm 6.28\,^{\text{a}}\) & \(47.3\pm 6.62\,^{\text{a}}\) & \(41.8\pm 5.85\,^{\text{ab}}\) & \(28.7\pm 4.02\,^{\text{b}}\) & 39 \\ \hline \multicolumn{7}{c}{Non-Essential} \\ \hline Ala & \(67.1\pm 9.40\,^{\text{a}}\) & \(67.6\pm 9.48\,^{\text{a}}\) & \(65.8\pm 9.21\,^{\text{a}}\) & \(68.7\pm 13.58\,^{\text{a}}\) & \(86.1\pm 12.06\,^{\text{a}}\) & \(121.9\pm 17.06\,^{\text{b}}\) \\ Arg & \(71.4\pm 10.00\,\) & \(72.6\pm 10.16\,\) & \(67.6\pm 9.47\,\) & \(64.8\pm 9.07\,\) & \(79.4\pm 11.11\,\) & \(94.1\pm 13.17\,^{\text{a}}\) \\ Asp & \(109.2\pm 15.29\,^{\text{a}}\) & \(107.8\pm 15.10\,^{\text{a}}\) & \(95.4\pm 13.36\,^{\text{ab}}\) & \(102.7\pm 14.38\,^{\text{a}}\) & \(106\pm 14.84\,^{\text{a}}\) & \(65.6\pm 9.17\,^{\text{b}}\) \\ Glu & \(146\pm 20.44\,\) & \(154.5\pm 21.62\,\) & \(141.2\pm 19.77\,^{\text{a}}\) & \(154.3\pm 21.61\,\) & \(161.7\pm 22.64\,^{\text{b}}\) & \(110.8\pm 15.5\,^{\text{c}}\) \\ Gly & \(79.5\pm 11.13\,^{\text{a}}\) & \(77.7\pm 10.87\,^{\text{a}}\) & \(94.9\pm 13.29\,^{\text{a}}\) & \(70.9\pm 9.92\,^{\text{a}}\) & \(161.7\pm 22.64\,^{\text{b}}\) & \(287\pm 40.1\,^{\text{c}}\) \\ Hyp & \(9.9\pm 1.97\,^{\text{a}}\) & \(10.4\pm 20.9\,^{\text{a}}\) & \(18.6\pm 3.73\,^{\text{a}}\) & \(11.6\pm 231\,^{\text{a}}\) & \(43.9\pm 8.78\,^{\text{b}}\) & \(96.8\pm 19.36\,^{\text{c}}\) \\ Orn & \(<0.05\,\) & \(<0.05\,\) & \(<0.05\,^{\text{c}}\) & \(<0.05\,^{\text{c}}\) & \(<0.05\,^{\text{c}}\) & \(<0.05\,^{\text{c}}\) \\ Pro & \(50.0\pm 7.00\,^{\text{ab}}\) & \(49.2\pm 6.89\,^{\text{ab}}\) & \(50.8\pm 7.12\,^{\text{ab}}\) & \(41.8\pm 5.86\,^{\text{a}}\) & \(73.3\pm 10.26\,^{\text{b}}\) & \(131.9\pm 18.47\,^{\text{c}}\) \\ Ser & \(53.3\pm 7.46\,\) & \(50.9\pm 7.12\,^{\text{a}}\) & \(49.7\pm 6.96\,^{\text{a}}\) & \(43.8\pm 6.12\,^{\text{a}  
therefore likely contains collagen [43]. This could be due to the proportionally high amount of fish skin in salmon by-products compared to, e.g., whole blue whiting (HYDR1). CONC3 differed from CONC1 and CONC2 samples only with tryptophan and even with that, the difference was minimal. This is consistent with other studies. For example, [PERSON] et al.