Decoding the Dynamic Evolution and Metabolic Pathways of Volatile and Non-Volatile Flavors in Prepared Fish Fillets during Boiling: An Integrated Approach of HS-SPME-GC-MS, HS-GC-IMS, E-Nose, and Chemometrics

Abstract This study examined how boiling time (0–150 s) affects the flavor of prepared grass carp fillets. Using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), we identified 146 volatile organic compounds (VOCs), of which 15 were defined as key odorants. Shorter boiling (30–60 s) enhanced the release of volatiles like 1-octen-3-ol and (Z)-4-heptenal, imparting mushroom and fruity notes. The 90 s stage featured nutty and oily aromas from compounds such as 2,5-dimethyl-3-isopropylpyrazine and heptanal. Extended boiling (120–150 s) led to the dominance of sweet and grassy notes from isoeugenol and propionaldehyde. The core free amino acids (FAAs)─aspartic acid (Asp), glutamic acid (Glu), and histidine (His)─shaped the primary taste profile, and VOC formation was closely linked to amino acid and nucleotide metabolism. This work provides a theoretical basis for optimizing the flavor quality of prepared fish products.