title: Investigation into the formation of guaiacol conjugates in berries and leaves of grapevine Vitis vinifera L. Cv. cabernet sauvignon using stable isotope tracers combined with HPLC-MS and MS/MS analysis.
abstract: Fermentation of grapes that had been exposed to bushfire smoke can potentially yield unpalatable, smoke-affected wine. Guaiacol and its glucoconjugate were previously found in smoke-affected grapes at an elevated concentration. To find and identify further guaiacol conjugates in smoke-affected grapes, a stable isotope feeding experiment combined with extensive HPLC-MS and MS/MS investigations was carried out. Leaves and berries of a potted grapevine were placed in contact with an aqueous mixture of d(0)- and d(3)-guaiacol for 1-2 days and collected 5 weeks later. Screening for potential guaiacol conjugates in the leaves and berries was facilitated by monitoring the unique mass spectrometric signature of an isotopic doublet separated by 3 Da. Seven different conjugates were detected in leaves and berries and were tentatively identified as mono- and diglycosides of guaiacol. Quantitative analysis demonstrated that the guaiacol conjugates were translocated between leaves and berries to a very limited extent and were also present as low-level natural compounds of untreated leaves and berries. The same guaiacol conjugates were also found at a considerably elevated concentration in leaves and berries obtained from grapevines exposed to bushfire smoke.
authors.affiliation: The Australian Wine Research Institute, PO Box 197, Glen Osmond, South Australia 5064, Australia. yoji.hayasaka@awri.com.au
authors.forename: Yoji
authors.initials: Y
authors.lastname: Hayasaka
authors.forename: Gayle A
authors.initials: GA
authors.lastname: Baldock
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Pardon
authors.forename: David W
authors.initials: DW
authors.lastname: Jeffery
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Herderich
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005638:Fruit / Q000737:chemistry*; D005960:Glucosides / Q000032:analysis / Q000302:isolation & purification; D006139:Guaiacol / Q000032:analysis* / Q000302:isolation & purification; D007553:Isotope Labeling; D013058:Mass Spectrometry / Q000379:methods; D018515:Plant Leaves / Q000737:chemistry*; D012906:Smoke; D013057:Spectrum Analysis / Q000379:methods; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D005960:Glucosides; D012906:Smoke; D006139:Guaiacol