Pyrazines are among the most important compound class conveying the odor impressions “roasty”, “nutty”, and “earthy”. They are formed by the Maillard reaction and occur ubiquitously in heated foods. The excretion of metabolites of the key flavor odorant 2,3,5-trimethylpyrazine, abundant in the volatile fraction of roasted coffee, was investigated. Based on literature suggestions, putative phase 1 and phase 2 metabolites were synthesized, characterized by nuclear magnetic resonance and mass spectroscopy data and used as standards for targeted, quantitative analysis of coffee drinkers’ urine using stable-isotope-dilution-ultrahigh-performance liquid chromatography tandem mass spectroscopy (SIDA-UHPLC–MS/MS). The analysis of spot urine samples from a coffee intervention study revealed 3,6-dimethylpyrazine-2-carboxylic acid, 3,5-dimethylpyrazine-2-carboxylic acid, and 5,6-dimethylpyrazine-2-carboxylic acid were quantitatively dominating metabolites. Only negligible traces of pyrazinemethanols (3,6-dimethyl-2-pyrazinemethanol and 3,5,6-trimethylpyrazine-2-ol), glucuronides ((3,6-dimethylpyrazine-2-yl-)methyl-O-β-D-glucuronide and (3,5-dimethylpyrazine-2-yl-)methyl-O-β-D-glucuronide), and sulfates ((3,6-dimethylpyrazine-2-yl-)methyl-sulfate and (3,5-dimethylpyrazine-2-yl-)methyl-sulfate) were detected.

中文翻译：

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人尿液中关键风味化合物 2,3,5-三甲基吡嗪的代谢物

吡嗪是最重要的化合物类别之一，具有“烘烤味”、“坚果味”和“泥土味”的气味印象。它们是由美拉德反应形成的，普遍存在于加热食品中。研究了烘焙咖啡挥发性成分中富含的关键风味气味剂 2,3,5-三甲基吡嗪的代谢物的排泄。根据文献建议，合成了假定的第 1 相和第 2 相代谢物，通过核磁共振和质谱数据进行表征，并用作使用稳定同位素稀释超高效液相色谱对咖啡饮用者尿液进行有针对性的定量分析的标准品串联质谱（SIDA-UHPLC-MS/MS）。对咖啡干预研究中的点尿样本的分析显示，3,6-二甲基吡嗪-2-羧酸、3,5-二甲基吡嗪-2-羧酸和5,6-二甲基吡嗪-2-羧酸是定量的主要代谢物。仅微量吡嗪甲醇（3,6-二甲基-2-吡嗪甲醇和 3,5,6-三甲基吡嗪-2-醇）、葡萄糖醛酸苷（(3,6-二甲基吡嗪-2-基-)甲基-O-β-D -葡萄糖苷酸和(3,5-二甲基吡嗪-2-基-)甲基-O-β-D-葡萄糖苷酸)，以及硫酸盐((3,6-二甲基吡嗪-2-基-)甲基硫酸盐和(3,5-检测到二甲基吡嗪-2-基-)甲基硫酸酯)。