Table 4.
Amino acid content of gilthead sea bream by-products (expressed as mg/100 g of tissue).
| Amino Acid | Muscle | Fishbone | Gills | Guts | Head | Liver | Skin | SEM | Sig. |
|---|---|---|---|---|---|---|---|---|---|
| Non-essential amino acids | |||||||||
| Aspartic acid | 1665.94 b | 1490.45 b | 873.88 a | 707.01 a | 974.51 a | 579.97 a | 1684.35 b | 67.50 | *** |
| Serine | 692.39 cd | 745.83 d | 500.13 ab | 384.69 a | 561.69 bc | 388.47 a | 781.13 d | 24.51 | *** |
| Glutamic acid | 2452.18 b | 2152.00 b | 1405.68 a | 1052.31 a | 1504.07 a | 1001.47 a | 2541.65 b | 95.44 | *** |
| Glycine | 947.23 ab | 1647.89 c | 1198.47 bc | 487.46 a | 1582.10 bc | 445.77 a | 1544.00 bc | 81.90 | *** |
| Alanine | 915.46 cd | 1023.35 cd | 778.60 bc | 449.63 a | 825.64 bc | 559.99 ab | 1156.33 d | 38.85 | *** |
| Proline | 571.67 ab | 932.44 b | 695.85 ab | 354.83 a | 883.46 b | 439.01 a | 948.60 b | 44.75 | ** |
| Tyrosine | 587.79 c | 455.09 b | 252.92 a | 246.60 a | 285.10 a | 219.13 a | 532.17 bc | 22.97 | *** |
| Total NE | 7832.65 abc | 8447.04 cd | 5705.50 ab | 3682.52 a | 6616.56 bc | 3633.82 a | 9188.23 d | 313.92 | *** |
| Essential amino acids | |||||||||
| Histidine | 561.41 c | 563.80 c | 345.73 ab | 242.66 a | 386.75 b | 251.50 a | 568.54 c | 20.05 | *** |
| Arginine | 1097.24 bc | 1293.64 bc | 228.41 a | 602.08 a | 985.48 b | 219.63 a | 1456.75 c | 63.22 | *** |
| Threonine | 833.56 e | 767.16 de | 629.81 cd | 413.81 ab | 541.25 bc | 308.63 a | 856.16 e | 30.20 | *** |
| Valine | 914.89 b | 803.34 b | 547.55 a | 498.03 a | 514.60 a | 566.24 a | 924.32 b | 32.55 | *** |
| Methionine | 346.52 d | 239.97 cd | n d a | n d a | 176.61 bc | 117.23 b | 285.22 c d | 18.24 | *** |
| Lysine | 1705.13 b | 1344.78 b | 796.11 a | 456.78 a | 814.16 a | 450.36 a | 1646.93 b | 76.79 | *** |
| Isoleucine | 801.69 b | 667.67 b | 377.97 a | 346.84 a | 387.14 a | 401.80 a | 769.59 b | 32.14 | *** |
| Leucine | 1284.54 b | 1101.44 b | 676.58 a | 557.71 a | 655.64 a | 664.71 a | 1290.07 b | 51.00 | *** |
| Phenylalanine | 736.54 b | 683.95 b | 423.38 a | 358.92 a | 440.62 a | 421.44 a | 737.63 b | 25.10 | *** |
| Total E | 8460.81 b | 7465.74 b | 4025.51 a | 3476.82 a | 4902.25 a | 3401.53 a | 8535.21 b | 332.90 | *** |
| E/NE | 1.08 c | 0.89 b | 0.71 a | 0.95 b | 0.75 a | 0.94 b | 0.94 b | 0.02 | *** |
| Taurine | 127.02 b | 148.67 bc | n d a | 335.20 e | 166.53 cd | n d a | 187.91 d | 10.76 | *** |
a–e Means in the same row with different letters differ significantly (p < 0.05; Duncan test). SEM: standard error of the mean. Sig.: significance; **: p < 0.01, ***: p < 0.001. E: essential amino acids. NE: non-essential amino acids. nd: not detected.