title: Purification and gas chromatography-combustion-isotope ratio mass spectrometry of aroma compounds from green tea products and comparison to bulk analysis.
abstract: A method for carbon isotope ratio (δ(13)C) analysis was developed for compound-specific isotope analysis of tea volatiles, and the values were compared with the δ(13)C value from bulk isotope analyses. The δ(13)C value of 2-phenylethanol liberated via enzymatic hydrolysis of the 2-phenylethyl β-primeveroside standard was examined first. Isotope fractionations for 2-phenylethyl β-primeveroside from preparative high-performance liquid chromatography (HPLC) were also analyzed. The enzymatic treatment and the preparative HPLC process did not cause carbon isotope fractionations, substantiating the strategies available for δ(13)C analysis of volatile compounds. On the basis of the gas chromatography-combustion-isotope ratio mass spectrometry data from 2-phenylethanol, it was possible to derive the conditions for enzyme treatment and preparative HPLC of the glycoconjugates of 2-phenylethanol, (Z)-3-hexenol, and benzyl alcohol isolated from green tea leaves. Larger variations in δ(13)C were found for individual volatile compounds compared with bulk analytical data from the leaves, indicating the potential to utilize this strategy in assigning the geographical origin of green tea.
authors.affiliation: Graduate School of Science and Technology, Shizuoka University , 836 Ohya, Shizuoka 422-8529, Japan.
authors.forename: Ariaki
authors.initials: A
authors.lastname: Murata
authors.forename: Ulrich H
authors.initials: UH
authors.lastname: Engelhardt
authors.forename: Peter
authors.initials: P
authors.lastname: Fleischmann
authors.forename: Keita
authors.initials: K
authors.lastname: Yamada
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yoshida
authors.forename: Dieter
authors.initials: D
authors.lastname: Juchelka
authors.forename: Andreas
authors.initials: A
authors.lastname: Hilkert
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohnishi
authors.forename: Naoharu
authors.initials: N
authors.lastname: Watanabe
authors.forename: Peter
authors.initials: P
authors.lastname: Winterhalter
mesh_terms: D019905:Benzyl Alcohol / Q000032:analysis; D028241:Camellia sinensis / Q000737:chemistry; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005504:Food Analysis / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006027:Glycosides / Q000032:analysis; D000441:Hexanols / Q000032:analysis; D009812:Odorants / Q000032:analysis*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D006027:Glycosides; D000441:Hexanols; D013662:Tea; C069905:phenethyl alcohol xylopyranosyl-(1-6)-glucopyranoside; C051918:3-hexen-1-ol; D019905:Benzyl Alcohol; D010626:Phenylethyl Alcohol