title: Role of glycoconjugates of 3-methyl-4-hydroxyoctanoic acid in the evolution of oak lactone in wine during oak maturation.
abstract: Oak lactone is a natural component of oak wood, but it also exists in glycoconjugate precursor forms. This study concerned the role of glycoconjugates of 3-methyl-4-hydroxyoctanoic acid, specifically a galloylglucoside, glucoside, and rutinoside, in the evolution of oak lactone during cooperage and maturation. The glycoconjugate profiles of 10 French oak samples were obtained by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using stable isotope dilution analysis. The galloylglucoside was found to be the predominant glycoconjugate precursor and ranged in concentration from 110 to 354 μg/g. Maturation trials indicated the galloylglucoside undergoes acid-catalyzed hydrolysis after extraction into wine; after 12 months of maturation, the glucoside was the most abundant precursor, present at between 2- and 11-fold higher concentrations than those observed for powdered oak. Thermal degradation of glycoconjugates was observed only when oak samples were heated at 200 °C for 30 min, demonstrating their thermal stability.
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA 5064, Australia. kerry.wilkinson@adelaide.edu.au
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Wilkinson
authors.forename: Andrei
authors.initials: A
authors.lastname: Prida
authors.forename: Yoji
authors.initials: Y
authors.lastname: Hayasaka
mesh_terms: D002210:Caprylates / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006001:Glycoconjugates / Q000737:chemistry*; D007554:Isotopes / Q000737:chemistry; D007783:Lactones / Q000737:chemistry; D029963:Quercus / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014920:Wine / Q000032:analysis*; D014934:Wood / Q000737:chemistry
chemical_list: C488157:3-methyl-4-hydroxyoctanoic acid; D002210:Caprylates; D006001:Glycoconjugates; D007554:Isotopes; D007783:Lactones