title: Application of a modified method for 3-mercaptohexan-1-ol determination to investigate the relationship between free thiol and related conjugates in grape juice and wine.
abstract: A method has been developed for determining 3-mercaptohexan-1-ol (3-MH) in wine and grape juice using gas chromatography with conventional electron ionization (EI) mass spectrometry. The limit of quantitation of 40 ng/L was achieved with excellent precision using stable isotope dilution analysis (SIDA) combined with headspace solid-phase microextraction (SPME) of derivatized 3-MH. This method was used in combination with HPLC-MS/MS analysis of the individual diastereomers of 3-S-cysteinylhexan-1-ol (Cys-3-MH) and 3-S-glutathionylhexan-1-ol (Glut-3-MH), which are known precursors of the volatile thiol 3-MH. Commercial and small-lot winemaking trials were evaluated to determine the concentrations of precursors and free 3-MH at various stages of grape processing and winemaking. Five Sauvignon blanc clones were also assessed for precursors and free thiol during ripening, revealing the presence of 3-MH in the unfermented juices and a stark increase in precursor concentrations in the latter stage of ripening. Additionally, differences due to sample freezing and mode of juice preparation were revealed for the precursors, and a set of commercially available wines was analyzed to investigate the amounts of precursors and free 3-MH in Sauvignon blanc and other white wine varieties. There was seemingly no relationship between precursor concentrations in juice and 3-MH concentrations in wine. This was somewhat understandable, because the formation of precursors appears to be a dynamic process affected by a multitude of factors, beginning with grape ripening and continuing during vinification.
authors: The Australian Wine Research Institute, Glen Osmond, South Australia, Australia.
authors: Dimitra L
authors: DL
authors: Capone
authors: Mark A
authors: MA
authors: Sefton
authors: David W
authors: DW
authors: Jeffery
mesh_terms: D001628:Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D052617:Solid Phase Microextraction / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D027843:Vitis / Q000737:chemistry* / Q000254:growth & development; D014920:Wine / Q000032:analysis*
chemical_list: C443379:3-mercaptohexan-1-ol; D013438:Sulfhydryl Compounds