气相色谱-静电场轨道阱高分辨质谱法辅助鉴定酱油未知的气味活性化合物

Identification of Unknown Aroma-active Compounds of Soy Sauce by Gas Chromatography-Orbitrap-Mass Spectrometry

以高盐稀态酱油为测试样品,采用气相色谱-静电场轨道阱高分辨质谱(gas chromatography-orbitrapmass spectrometry,GC-Orbitrap-MS)法、辅助气相色谱-单四极杆质谱-嗅闻(gaschromatography-quadruple-mass spectrometry-olfactometry,GC-Q-MS-O)联用法鉴定"未知"气味活性化合物。GC-Q-MS和GC-Orbitrap-MS分别鉴定出91种和166种挥发性化合物,Orbitrap-MS检出总峰面积为单四极杆质谱的31倍。GC-Q-MS-O结果分析中有4处较强的香气活性区域"果香"、"果香"、"清香,草香"、"花果香",无鉴定结果。利用高分辨OrbitrapMS技术,通过高质量精度的质谱数据推算化合物碎片及其天然同位素组成,辅助以NIST谱库比对、保留指数及香气特征等信息,全面定性4个未知香气活性物质为异丁酸乙酯、丁酸乙酯、3-己烯-2-酮和异佛尔酮。结果表明,GC-Orbitrap-MS辅助分析GC-Q-MS-O数据,能够有效地鉴定出含量低于单四极杆质谱检出限,或因与其他物质重叠而无法准确定性的未知气味活性化合物,对于风味化学领域香气活性物质的深度挖掘具有重要意义。

Gas chromatography-orbitrap-mass spectrometry(GC-Orbitrap-MS)combined with gas chromatographyquadruple-mass spectrometry-olfactometry(GC-Q-MS-O)was used to identify the‘unknown’aroma active compounds of soy sauce in this study.GC-Q-MS and GC-Orbitrap-MS identified 91 and 166 volatile compounds,respectively.The total peak area detected by Orbitrap-MS was 31 times as large as that detected by Q-MS.Four intense aroma-active areas with‘fruity’,‘fruity’,‘grassy’and‘flowery and fruity’notes were not identified in GC-Q-MS-O.In order to identify the 4 unknown compounds,the compound fragments and natural isotopic compositions were estimated by GC-Orbitrap-MS based on the high-precision mass spectral data.In addition,by comparing the mass spectra with the NIST mass spectral library as well as considering the retention index and aroma characteristics,they were identified as ethyl isobutyrate,ethyl butyrate,3-hexen-2-one and 3,5,5-trimethyl-2-cyclohexenone(isophorone).This study showed that GC-Orbitrap-MS combined with GC-Q-MS-O could effectively reveal the‘unknown’aroma-active compounds whose contents were below the detection limit of quadrupole MS,or which could not be determined due to overlapping with other volatiles,which would be of important significance for the identification of aroma-active compounds in the field of flavor chemistry.