Analysis of volatiles in Dezhou Braised Chicken by comprehensive two-dimensional gas chromatography/high resolution-time of flight mass spectrometry
A fast and mild extraction method and an accurate identification method to analyze the volatiles in non-volatile food matrices were set up. The accelerated solvent extraction followed by solvent assisted flavor evaporation (ASE-SAFE) was used to extract the volatiles from Dezhou braised chicken. The extract was analyzed by a comprehensive two-dimensional gas chromatography/high resolution-time of flight mass spectrometry (GC × GC/HR-TOFMS) and a GC-qMS. Ninety one compounds were identified by GC × GC/HR-TOFMS with an aid of the NIST08 library and accurate mass determination, 44 compounds were identified by GC-qMS only with the NIST08 library. The main odor-active constitutes of the Dezhou braised chicken were carbonyl compounds (33.04%). 2-Enals and 2,4-dineals were considered to be the most important odor-active constitutes in chicken. In our study, 6 very polar and unstable 2-enals or 2,4-dineals compounds, including (E)-2-hexenal, (E)-2-nonenal, (Z)-2-decenal, (E)-2-undecenal, (E,E)-2,4-heptadienal and (E,E)-2,4-nonadienal, were only identified by GC × GC/HR-TOFMS. Three very polar and unstable furanones, including 5-acetyldihydro-2(3H)-furanone (0.04%), dihydro-3-hydroxy-4,4-dimethyl-2(3H)-furanone (0.32%) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (0.32%) were also only detected by the GC × GC/HR-TOFMS. Some trace sulfur-containing and nitrogen-containing compounds, including disulfide dipropyl (0.05%), 2-acetylthiazole (0.06%), 2-pyrrolidinone (0.15%) and benzothiazole (0.07%) that might play important roles in the flavor of chicken, were also only found by the GC × GC/HR-TOFMS.