Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
J Agric Food Chem. 2011 Sep 14;59(17):9065-73. doi: 10.1021/jf201716w. Epub 2011 Aug 8.
Coffee was characterized by proton and carbon nuclear magnetic resonance (NMR) spectroscopy. To identify the coffee components, a detailed and approximately 90% signal assignment was carried out using various two-dimensional NMR spectra and a spiking method, in which authentic compounds were added to the roasted coffee bean extract (RCBE) sample. A total of 24 coffee components, including 5 polysaccharide units, 3 stereoisomers of chlorogenic acids, and 2 stereoisomers of quinic acids, were identified with the NMR spectra of RCBE. On the basis of the signal assignment, state analyses were further launched for the metal ion-citrate complexes and caffeine-chlorogenate complexes. On the basis of the signal integration, the coffee components were successfully quantified. This NMR methodology yielded detailed information on RCBE using only a single observation and provides a systemic approach for the analysis of other complex mixtures.
采用质子和碳核磁共振（NMR）光谱对咖啡进行了表征。为了鉴定咖啡成分，使用各种二维 NMR 光谱和加标法进行了详细的、约 90%信号分配，其中将纯化合物添加到烘焙咖啡豆提取物（RCBE）样品中。通过 RCBE 的 NMR 光谱，共鉴定出 24 种咖啡成分，包括 5 个多糖单元、3 种绿原酸立体异构体和 2 种奎宁酸立体异构体。基于信号分配，进一步对金属离子-柠檬酸络合物和咖啡因-绿原酸盐络合物进行了状态分析。基于信号积分，成功地对咖啡成分进行了定量。该 NMR 方法仅使用单个观察值即可提供有关 RCBE 的详细信息，并为分析其他复杂混合物提供了系统的方法。
