Chair of Food Chemistry and Molecular and Sensory Science, Technische Universität München, Lise-Meitner-Str. 34, D-85354 Freising, Germany.
J Agric Food Chem. 2022 May 4;70(17):5427-5437. doi: 10.1021/acs.jafc.2c01378. Epub 2022 Apr 25.
A holistic ultraperformance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry-based approach was used to screen for storage-induced reaction products consisting of the volatile key coffee thiols methanethiol, 2-furfurylthiol, 2-methyl-3-furanthiol, 3-mercapto-3-methylbutanol, and 3-mercapto-2-butanone and low-molecular weight phenolic constituents of coffee beverages including chlorogenic acid, caffeic acid, and their thermal degradation products hydroxyhydroquinone, catechol, and 4-ethylcatechol. Multiple marker compounds could be detected in thiol-enriched coffee brews after UPLC-TOF-MS profiling and statistical data analysis. Subsequently, marker compounds were synthesized and structurally characterized via high-resolution mass spectrometry and 1D- and 2D-NMR experiments. Quantification of these reaction products in fresh and stored coffee beverages was realized in native coffee and after stir bar sorptive extraction with liquid desorption by means of UHPLC-MS/MS. The quantitative data revealed the biggest influence of storage time on the formation of reaction products between hydroxyhydroquinone and methanethiol and 2-furfurylthiol, while other reaction products were only slightly affected by storage and thus most likely formed during the roasting process.
采用整体超高效液相色谱（UPLC）-飞行时间（TOF）-质谱法筛选由挥发性关键咖啡硫醇甲硫醇、2-糠基硫醇、2-甲基-3-呋喃硫醇、3-巯基-3-甲基-1-丁醇和 3-巯基-2-丁酮以及咖啡饮料中的低分子量酚类成分组成的储存诱导反应产物，包括绿原酸、咖啡酸及其热降解产物羟基氢醌、儿茶酚和 4-乙基儿茶酚。在 UPLC-TOF-MS 分析和统计数据分析后，可在富含硫醇的咖啡酿造物中检测到多种标记化合物。随后，通过高分辨率质谱和 1D-和 2D-NMR 实验合成并对标记化合物进行结构表征。通过 UHPLC-MS/MS 采用原位咖啡和搅拌棒吸附萃取后的液体解吸对新鲜和储存咖啡饮料中的这些反应产物进行定量。定量数据表明，储存时间对羟基氢醌与甲硫醇和 2-糠基硫醇之间形成反应产物的影响最大，而其他反应产物受储存的影响较小，因此最有可能在烘焙过程中形成。
