Synthesis and Structure Determination of Covalent Conjugates Formed from the Sulfury−Roasty-Smelling 2-Furfurylthiol and Di- or Trihydroxybenzenes and Their Identification in Coffee Brew
| Autor: | Sarah Hemmersbach, Christoph Müller, Gordon van't Slot, Thomas Hofmann |
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| Rok vydání: | 2006 |
| Předmět: |
chemistry.chemical_classification
Catechol Magnetic Resonance Spectroscopy Molecular Structure Phenol biology General Chemistry biology.organism_classification Coffee Mass Spectrometry chemistry.chemical_compound chemistry Chlorogenic acid Pyrogallol Sulfanyl Odorants Thiol Caffeic acid Organic chemistry Sulfhydryl Compounds Phenols Furans General Agricultural and Biological Sciences Chromatography High Pressure Liquid Aroma |
| Zdroj: | Journal of Agricultural and Food Chemistry. 54:10076-10085 |
| ISSN: | 1520-5118 0021-8561 |
| DOI: | 10.1021/jf062728q |
| Popis: | Recent investigations demonstrated that the reaction of odor-active thiols such as 2-furfurylthiol with thermally generated chlorogenic acid degradation products is responsible for the rapid aroma staling of coffee beverages. To get a clear understanding of the molecular mechanisms underlying this aroma staling, the existence of putative phenol/thiol conjugates needs to be verified in coffee. The aim of the present study was therefore to synthesize such conjugates for use as reference substances for LC-MS screening of coffee. To achieve this, catechol, 3-methyl-, 4-methyl-, and 4-ethylcatechol, pyrogallol, hydroxyhydroquinone, 5-O-caffeoylquinic acid, and caffeic acid, respectively, were reacted with 2-furfurylthiol in the presence of iron(III) chloride and air oxygen. After purification, the structures of 25 phenol/thiol conjugates were identified by means of LC-MS/MS and 1D/2D NMR experiments. Using these compounds as reference materials, four conjugates, namely, 3-((2-furylmethyl)sulfanyl)catechol, 3-((2-furylmethyl)sulfanyl)-5-ethylcatechol, 4-((2-furylmethyl)sulfanyl)hydroxyhydroquinone, and 3,4-bis((2-furylmethyl)sulfanyl) hydroxyhydroquinone, were identified for the first time in coffee brew by means of HPLC-MS/MS(MRM). These findings clearly demonstrate catechol, 4-ethylcatechol, and hydroxyhydroquinone as the primary thiol trapping agents involved in the aroma staling of coffee beverages. |
| Databáze: | OpenAIRE |
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