title: Determination of oak lactones in barrel-aged wines and in oak extracts by stable isotope dilution analysis.
abstract: The cis- and trans-isomers of 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone, the so-called oak lactones, are derived from oakwood, and the cis-isomer is an important contributor to wine flavour. Their deuterium-labelled forms, [2H4]cis-oak lactone and [2H4]trans-oak lactone, were synthesised from the unlabelled analogues, and were utilised in a new method employing gas chromatography-mass spectrometry to determine the concentration of these compounds in wine or extracts of oak shavings in a single analysis. The method can employ either liquid-liquid extraction or solid-phase microextraction, and is both rapid and accurate. There was some artefactual generation of cis-oak lactone during the analysis of model wine extracts of unheated oak shavings when diethyl ether extraction and injector block temperatures at or above 225 degrees C were employed.
authors.affiliation: The Australian Wine Research Institute, Glen Osmond, SA, Australia. apollnitz@awri.adelaide.edu.au
authors.forename: A P
authors.initials: AP
authors.lastname: Pollnitz
authors.forename: G P
authors.initials: GP
authors.lastname: Jones
authors.forename: M A
authors.initials: MA
authors.lastname: Sefton
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007554:Isotopes; D007783:Lactones / Q000032:analysis*; D015203:Reproducibility of Results; D014920:Wine / Q000032:analysis*; D014934:Wood
chemical_list: D007554:Isotopes; D007783:Lactones