山西老陈醋熏醅过程中吡嗪类生成规律分析

Formation rules of pyrazines in the fumigation process of Shanxi aged vinegar

分析山西老陈醋熏醅过程中陶缸不同位点醋醅温度及吡嗪类物质含量的变化,研究传统熏醅中吡嗪类的形成规律。结果表明,在5 d的熏醅过程中,陶缸内的醋醅温度始终存在较大温差(10~52℃);共检测出2,3,5-三甲基吡嗪、2-乙基-5-甲基吡嗪、2-乙基-6-甲基吡嗪、2-乙基-3,5,6-三甲基吡嗪、4-甲基吡嗪和2,3-二甲基吡嗪6种吡嗪类化合物。陶缸不同位点生成和积累吡嗪类化合物的规律有显著差异。4-甲基吡嗪生成和积累速度最快,熏醅第1天除中部中心位点外其他位点均有生成,起始生成位点最低温度为40℃,含量为1.52 mg/kg;2,3,5-三甲基吡嗪生成和积累速度次之,最早在第1天陶缸边缘位点生成,起始生成位点最低温度为70℃,含量为0.11 mg/kg。其他4种吡嗪类主要在醋醅中部或顶部温度高于90℃的位点生成,且含量较低。主成分分析(PCA)结果表明,熏醅3~5 d的不同位点可根据吡嗪含量分为3类,其中第5天中部中心和中部1/2处最有利于吡嗪类积累。该研究进一步明确了熏醅过程中不同吡嗪类的生成顺序及其在陶缸中生成、积累的位置和温度信息。

The changes of temperature and pyrazines contents in the fermented grains of Shanxi aged vinegar in different points of the pottery jar were analyzed,and the formation rules of pyrazines in the traditional fumigation grains were studied.The results showed that there was a large temperature difference(10-52℃)in the vinegar fermented grains during 5 d of fumigation.A total of 6 pyrazine compounds including 2,3,5-trimethylpyrazine,2-ethyl-5-methylpyrazine,2-ethyl-6-methylpyrazine,2-ethyl-3,5,6-trimethylpyrazine,4-methylpyrazine,and 2,3-dimethylpyrazine were detected.There were significant differences in the formation and accumulation of pyrazine compounds at different sites.The formation and accumulation rate of 4-methylpyrazine was the fastest.On the first day of fumigation of fermented grains,4-methylpyrazine was formed at all sites except the central site.The lowest temperature of the initial site was 40℃,and the content was 1.52 mg/kg.The formation and accumulation rate of 2,3,5-trimethylpyrazine was followed by that of 4-methylpyrazine,which was first generated at the edge site of the pottery jar on the first day,with the lowest temperature of the initial production site of 70℃,and the content was 0.11 mg/kg.The other 4 kinds of pyrazines were mainly produced in the middle or top of fermented grains,where the temperature was higher than 90℃,and the content was low.The result of principal component analysis(PCA)showed that the sites of fermented grains at 3-5 d could be divided into three categories according to the pyrazines,among which the middle center and the middle 1/2 were the most favorable for pyrazines accumulation on the 5th day.The study further clarified the formation sequence of different pyrazines during the process of fumigation grains and the positions and temperature information of the formation and accumulation in the pottery jar.