Abstract: In order to investigate the effect of freezing methods on the volatile flavor of grass carp meat, three different freezing methods, namely quick freezing, ethanol immersion freezing and refrigerator freezing, were used to pretreat the fresh dorsal meat and red meat of grass carp. A new type of material (MonoTrap) was applied as a solid phase extraction (SPE) stationary phase to extract the volatile compounds of fish meat. The volatile flavor components were analyzed and identified by electronic nose and gas chromatography-mass spectrometry (GC-MS). The odors of fresh and frozen grass carp meat could be clearly discriminated by electronic nose. Principal component analysis (PCA) showed that the differences in odor components between ordinary refrigerator freezing and fresh meat was maximum. By GC-MS analysis, 45, 33, 28 and 22 volatile compounds were identified in fresh, quick-frozen, ethanol immersion frozen and refrigerator frozen dorsal meat, respectively, and 49, 38, 33 and 25 volatile compounds were detected in fresh, quick-frozen, ethanol immersion frozen and refrigerator frozen red meat, respectively. The main volatile compounds were aldehydes and alcohols. Also, this study demonstrated that pentanal, hexanal, heptanal, octanal, 2-octenal, nonanal, 2-nonenal, decanal, 2-decenal, undecanal, 2,4-decadienal, hexanol, 2-octen-1-ol, 1-octen-3-ol, and xylene made an important contribution to the overall flavor of grass carp meat. In terms of the type and amount of volatile components, fresh fish meat was similar to the quick-frozen sample but dissimilar to the refrigerator frozen sample. Conclusively, quick freezing was more beneficial to maintaining the quality of grass carp meat, and the flavor of frozen fish meat was similar to that of fresh fish.

Key words: grass carp, freezing, electronic?nose, gas?chromatography-mass spectrometry, volatile compounds