山西老陈醋晾晒前、后挥发性香味物质比较分析

Comparison of Volatile Flavor Compounds in Shanxi Aged Vinegar before and after Aging

山西老陈醋晾晒前、后样品采用同时蒸馏萃取处理,然后气-质谱联机、稀释法气相色谱-嗅闻分析。基于保留指数、质谱、标准品,气-质谱联机分析共鉴定出183种挥发性化合物,包括含硫化合物、含氮杂环、含氧杂环、醛类、酮类、醇类、酸类、酯类、酚类、醚类、其它类。两种醋中主要挥发性化合物均包括乙酸、乙偶姻、糠醛、2,3-丁二酮等,而晒后醋中吡嗪类化合物尤其四甲基吡嗪的含量显著增加。基于保留指数、气味特征、气-质谱联机鉴定结果、标准品,从两种醋中共鉴定出50种香气活性物质,其中晒前醋中稀释因子高的为乙酸、乙偶姻、2,3-丁二酮、乳酸乙酯、愈创木酚等10种化合物,晒后醋中稀释因子高的为3-甲硫基丙醇、糠醛、苯乙醛、愈创木酚等20种化合物。相比之下,醋晾晒前后主要变化为酯类物质减少,一些含氮杂环化合物尤其是吡嗪类化合物及含硫化合物的含量增加。研究结果可为山西老陈醋生产工艺的升级改造提供基础数据。

The samples of Shanxi aged vinegar before and after aging were treated by simultaneous distillation and solvent extraction(SDE).The extracts from the two vinegars were analyzed by gas chromatography-mass spectra(GC-MS)and gas chromatography-olfactometry(GC-O).Based on retention indices,mass spectra,and injection of authentic standards,a total of 184 volatile compounds were identified,including sulfur-containing compounds,nitrogen-containing heterocycles,oxygen-containing heterocycles,aldehydes,ketones,alcohols,acids,esters,phenols,ethers,and others.The major volatile compounds found in both the vinegars before and after aging included acetic acid,acetoin,furfural,2,3-butanedione,etc.However,compared to the vinegar before aging,the amounts of pyrazine compounds,especially tetramethylpyrazine,were markedly increased in the aged vinegar.By GC-O analysis,according to retention indices,sniffed odor characteristics,identifications in the GC-MS,and comparison of the analytical parameters with those of the authentic standards,a total of 23 odor-active compounds were identified,where 10 compounds were found with high FD values in the vinegar before aging,including acetic acid,acetoin,2,3-butanedione,ethyl lactate,guaiacol,etc;and 20 compounds were found with high FD values in the vinegar after aging,including 3-methyl propyl alcohol,furfural,phenylacetyldehyde,guaiacol,etc.Comparatively,after aging mainly the odorants of esters were decreased while those of the nitrogen-containing heterocyclic compounds(especially the pyrazine compounds)and the sulfur-containing compounds were increased in the vinegars.The research results are expected to provide guidance for upgrading production technology of the Shanxi aged vinegar.