title: Influence of grape-harvesting steps on varietal thiol aromas in Sauvignon blanc wines.
abstract: The intense tropical fruit aroma of Sauvignon blanc wines has been associated with the varietal thiols 3-mercaptohexanol (3MH), derived from odorless precursors in the grape, and 3-mercaptohexyl acetate (3MHA), arising from 3MH during fermentation. Grapes and juice were sourced from five locations in Marlborough, New Zealand, taking hand-picked grapes and samples at four stages during the mechanical harvesting process and pressing, which were then fermented in replicated 750 mL bottles. With each set of juices, the highest concentrations of Cys-3MH and Glut-3MH were found in the juices pressed to 1 bar, but these juices produced wines with lower 3MH and 3MHA concentrations. With three of the juices, there was an increase in varietal thiol content for wines made from juices that had been machine harvested compared to the hand-picked samples, which matched earlier findings of lower 3MH and 3MHA levels in wines made from hand-picked grapes. Juices that were more oxidized, and which showed a higher absorbance at 420 nm, were found to produce wines with lower 3MH and 3MHA concentrations.
authors.affiliation: Wine Science Programme, School of Chemical Sciences, The University of Auckland , Private Bag 92019, Auckland, New Zealand.
authors.forename: Thomas
authors.initials: T
authors.lastname: Allen
authors.forename: Mandy
authors.initials: M
authors.lastname: Herbst-Johnstone
authors.forename: Melanie
authors.initials: M
authors.lastname: Girault
authors.forename: Paul
authors.initials: P
authors.lastname: Butler
authors.forename: Gerard
authors.initials: G
authors.lastname: Logan
authors.forename: Sara
authors.initials: S
authors.lastname: Jouanneau
authors.forename: Laura
authors.initials: L
authors.lastname: Nicolau
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kilmartin
mesh_terms: D000085:Acetates / Q000032:analysis; D000383:Agriculture / Q000379:methods*; D001628:Beverages / Q000032:analysis; D005285:Fermentation; D005511:Food Handling / Q000379:methods; D005638:Fruit / Q000737:chemistry* / Q000254:growth & development; D000441:Hexanols / Q000032:analysis; D009520:New Zealand; D009812:Odorants / Q000032:analysis*; D013438:Sulfhydryl Compounds / Q000032:analysis*; D027843:Vitis; D014920:Wine / Q000032:analysis*
chemical_list: D000085:Acetates; D000441:Hexanols; D013438:Sulfhydryl Compounds; C513640:3-mercaptohexyl acetate; C477019:3-mercaptohexanol