Odor-active volatile compounds profile of triploid rainbow trout with different marketable sizes

The present study identified the volatile compounds profile in raw muscle of triploid rainbow trout with different marketable sizes (eviscerated weight: 2 kg, 3 kg and 4 kg, respectively). Six fish per each size treatment were sampled in a local commercial trout farm, then raw muscles of sampled fish were filleted to detect the volatile compounds by using the gas chromatography-mass spectrometry (GCMS) analysis coupled with automated solid-phase microextraction (SPME) system. Results showed that a total of 58 volatile compounds were identified in raw muscle of triploid rainbow trout, including aldehydes (20 species), ketones (6 species), alcohols (9 species), hydrocarbons (11 species), aromatics (6 species) and miscellaneous compounds groups (6 species). The subtotal estimated concentration of aldehydes group was significantly higher than those of the other volatile groups (P < 0.05). Based on the odor activity value (OAV ≥ 1), 21 odor-active compounds may contribute to the overall odor, including pentanal, hexanal, (Z)-4-heptenal, heptanal, (E)-2-heptenal, octanal, (E,E)-2,4-heptadienal, (E)-2-octenal, nonanal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, decanal, (E,E)-2,4-nonadienal, (E)-2-decenal, undecanal, 2,3-pentanedione, 2,3-octanedione, 1-heptanol, 1-octen-3-ol, 2-ethyl-furan and 2-pentyl-funan. The marketable fish of 2 kg had the most numerous volatiles species and the highest total estimated concentration. The profile of 58 identified volatile compounds in 2 kg fish was different with it in 3 kg and 4 kg fish. However, there was no difference in the total odor activity value of all odor-active compounds among three size treatments (P > 0.05). Based on the principle component analysis and cluster analysis using the odor activity values of 21 odor-active compounds, the overall odors of raw muscle might be similar in triploid rainbow trout with different marketable sizes.