Structure Determination of 3-O-Caffeoyl-epi-γ-quinide, an Orphan Bitter Lactone in Roasted Coffee

详细信息    查看全文

• 作者：Oliver Frank ; Simone Blumberg ; Gudrun Krü ; mpel ; Thomas Hofmann
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2008
• 出版时间：October 22, 2008
• 年：2008
• 卷：56
• 期：20
• 页码：9581-9585
• 全文大小：171K
• 年卷期：v.56,no.20(October 22, 2008)
• ISSN：1520-5118

文摘

Recent investigations on the bitterness of coffee as well as 5-O-caffeoyl quinic acid roasting mixtures indicated the existence of another, yet unknown, bitter lactone besides the previously identified bitter compounds 5-O-caffeoyl-muco-γ-quinide, 3-O-caffeoyl-γ-quinide, 4-O-caffeoyl-muco-γ-quinide, 5-O-caffeoyl-epi-δ-quinide, and 4-O-caffeoyl-γ-quinide. In the present study, this orphan bitter lactone was isolated from the reaction products generated by dry heating of 5-O-caffeoylquinic acid model, and its structure was determined as the previously unreported 3-O-caffeoyl-epi-γ-quinide by means of liquid chromatography−mass spectrometry (LC-MS) and one-/two-dimensional NMR experiments. The occurrence of this bitter lactone, exhibiting a low bitter recognition threshold of 58 μmol/L, in coffee beverages could be confirmed by LC-MS/MS (negative electrospray ionization) operating in the multiple reaction monitoring mode.