Analysis of Key Aroma Compound Changes in Grass Carp Fillets during Cold Storage Using Two-Dimensional Gas Chromatography–Olfactometry–Mass Spectrometry and Odor Activity Value

This study analyzed the changes in key aroma compounds in grass carp fillets during cold storage using aroma extract dilution analysis, odor activity values, and aroma recombination. A total of 11, 13, and 14 volatile compounds were recombined to construct recombination models representing the odor of fillets at 0, 3, and 7 days of cold storage, respectively. The key aroma compounds in fresh fillets included hexanal, (Z)-4-heptenal, nonanal, (E,E)-2,4-octadienal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, decanal, (E)-2-decenal, (E,E)-2,4-decadienal, 1-octen-3-ol, and 2,3-pentanedione. Moreover, (E)-2-octenal, 2-cyclopenten-1-one, γ-dodecalactone, and octanoic acid became the key aroma compounds after 3 and 7 days of refrigeration, respectively. (Z)-4-Heptenal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, decanal, and (E,E)-2,4-decadienal indicated the deterioration in flavor quality of fillets, which rose by 38.29 μg/kg (0–7 days). This study clarifies the key aroma compounds and characteristic compounds responsible for odor changes during the cold storage of fillets, establishing a basis for future improvement in odor quality during cold storage.