title: First identification of 4-S-glutathionyl-4-methylpentan-2-one, a potential precursor of 4-mercapto-4-methylpentan-2-one, in Sauvignon Blanc juice.
abstract: The identification of 4-S-glutathionyl-4-methylpentan-2-one (glut-4-MMP) by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) experiments in a Sauvignon Blanc juice extract is described. Synthesis of an authentic reference compound enabled confirmation of the presence of glut-4-MMP in a Sauvignon Blanc juice for the first time. The juice extract was obtained by batch-wise percolation of 6 L of juice through a sintered glass funnel packed with C18 sorbent, followed by further purification using low-pressure chromatography on C18. Analysis of the juice extract revealed a chromatographic peak with the same retention time and mass spectrum as the synthetic reference compound, and spiking experiments verified the findings. The presence of glut-4-MMP in grape juice may be related to the biosynthesis of the relevant S-cysteinyl conjugate and, subsequently, to the formation of aroma-active 4-mercapto-4-methylpentan-2-one (4-MMP). This compound has a very low reported sensory threshold (3 ng/L) in wine and is partially responsible for the aromas that are important to the quality and style of some wine varieties.
authors.affiliation: Chemical Sciences Department, University of Padova, Padova, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Fedrizzi
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Pardon
authors.forename: Mark A
authors.initials: MA
authors.lastname: Sefton
authors.forename: Gordon M
authors.initials: GM
authors.lastname: Elsey
authors.forename: David W
authors.initials: DW
authors.lastname: Jeffery
mesh_terms: D001628:Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005638:Fruit / Q000737:chemistry*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000032:analysis; D009812:Odorants / Q000032:analysis; D010422:Pentanones / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D027843:Vitis / Q000737:chemistry*
chemical_list: C538821:4-S-glutathionyl-4-methylpentan-2-one; C501638:4-mercapto-4-methyl-pentan-2-one; D010422:Pentanones; D010936:Plant Extracts; D013438:Sulfhydryl Compounds; D005978:Glutathione