Exploration of the changes in volatile flavor compounds of low salt dry-curing grass carp (Ctenopharyngodon idella) blocks during cold storage detected by E-nose, HS-SAFE-GC-MS and HS-GC-IMS

Low salt dry-curing (LSD) has emerged in the fish blocks during refrigeration with premade cuisine in recent years. However, the changes in flavor quality have not been explored systematically. Therefore, this study analyzed the flavor changes in the LSD-pretreated grass carp blocks stored at 4 degrees C and screened out the key volatile organic compounds, alongside the untreated ones as a control. The electronic nose (E-nose) combined with principal component analysis (PCA) could successfully distinguish the LSD-pretreated and untreated blocks. A total of 87 and 50 volatile organic compounds in the LSD-pretreated grass carp blocks at different refrigeration stages were identified by headspace solvent-assisted flavor evaporation-gas chromatography-mass spectrometry (HS-SAFE-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) respectively. According to the GC-MS data, 24 key volatile organic compounds with an odor activity value (OAV) over 1.0 were identified in the LSD-pretreated grass carp blocks at different refrigeration stages, including alcohols, aldehydes, aromatic compounds, aldol ketones, nicotinamide, and esters. The combination of E-nose, HS-SAFE-GC- MS, and HS-GC-IMS could comprehensively reflect the changes of volatile components in LSD-pretreated grass carp blocks at different refrigeration stages. It helps to understand further the mechanism of inhibiting the flavor deterioration of LSD-pretreated grass carp blocks.