title: Relationship between Menthiafolic Acid and Wine Lactone in Wine.
abstract: Menthiafolic acid (6-hydroxy-2,6-dimethylocta-2,7-dienoic acid, 2a) was quantified by GC-MS in 28 white wines, 4 Shiraz wines, and for the first time in 6 white grape juice samples. Menthiafolic acid was detected in all but one of the wine samples at concentrations ranging from 26 to 342 μg/L and in the juice samples from 16 to 236 μg/L. Various model fermentation experiments showed that some menthiafolic acid in wine could be generated from the grape-derived menthiafolic acid glucose ester (2b) during alcoholic and malolactic fermentation. Samples containing high concentrations of menthiafolic acid were also analyzed by enantioselective GC-MS and were shown to contain this compound in predominantly the (S)-configuration. Enantioselective analysis of wine lactone (1) in one of these samples, a four-year-old Chardonnay wine showed, for the first time, the presence of the 3R,3aR,7aS isomer of wine lactone (1b), which is the enantiomer of the form previously reported as the sole isomer present in young wine samples. The weakly odorous 3R,3aR,7aS 1b form comprised 69% of the total wine lactone in the sample. On the basis of the enantioselectivity of the hydrolytic conversion of menthiafolic acid to wine lactone at pH 3.0 determined previously and the relative proportions of (R)- and (S)-menthiafolic acid in the Chardonnay wine, the predicted ratio of wine lactone enantiomers that would be formed from hydrolysis at ambient temperature of the menthiafolic acid present in this wine was close to the ratio measured, which was consistent with menthiafolic acid being the major or sole precursor to wine lactone in this sample.
authors: Department of Wine Science, School of Agriculture, Food and Wine, The University of Adelaide , Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
authors: Joanne
authors: J
authors: Giaccio
authors: The Australian Wine Research Institute , P.O. Box 197, Glen Osmond, South Australia 5064, Australia.
authors: Chris D
authors: CD
authors: Curtin
authors: Department of Wine Science, School of Agriculture, Food and Wine, The University of Adelaide , Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
authors: Mark A
authors: MA
authors: Sefton
authors: Department of Wine Science, School of Agriculture, Food and Wine, The University of Adelaide , Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
authors: Dennis K
authors: DK
authors: Taylor
mesh_terms: D001628:Beverages / Q000032:analysis; D002210:Caprylates / Q000032:analysis*; D005231:Fatty Acids, Unsaturated / Q000032:analysis*; D005285:Fermentation; D005638:Fruit / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007783:Lactones / Q000032:analysis*; D009812:Odorants / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013237:Stereoisomerism; D027843:Vitis / Q000737:chemistry; D014920:Wine / Q000032:analysis*
chemical_list: D002210:Caprylates; D005231:Fatty Acids, Unsaturated; D007783:Lactones; D005947:Glucose
keywords: aroma; enantioselective analysis; flavor; hydrolysis; precursor; wine; wine lactone