期刊
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
卷 64, 期 38, 页码 7298-7306出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jafc.6b02472
关键词
epi-quinic acid; muco-quinic acid; cis-quinic acid; scyllo-quinic acid; coffee
资金
- Mondelez
- Jacobs University Bremen gGmbH
(-)-Quinic acid possess eight possible stereoisomers, which occur both naturally and as products of thermal food processing. In this contribution, we have selectively synthesized four isomers, namely, epi-quinic acid, muco-quinic acid, cis-quinic acid, and scyllo-quinic acid, to develop a tandem LC-MS method identifying all stereoisomeric quinic acids. Four derivatives have been unambiguously characterized by single-crystal X-ray crystallography. The missing diastereomers of quinic acid were obtained by nonselective isomerization of (-)-quinic acid using acetic acid/concentrated H2SO4 allowing chromatographic separation and assignment of all diastereomers of quinic acid. We report for the first time that a full set of stereoisomers are reliably distinguishable on the basis of their tandem mass spectrometric fragment spectra as well as their elution order. A rationale for characteristic fragmentation mechanisms is proposed. In this study, we also observed that muco-quinic acid, scyllo-quinic acid, and epi-quinic acid are present in hydrolyzed Guatemalan roasted coffee sample as possible products of roasting.
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