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https://hdl.handle.net/2440/55038
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Type: | Journal article |
Title: | Odor detection thresholds and enantiomeric distributions of several 4-alkyl substituted γ-lactones in Australian red wine |
Other Titles: | Odor detection thresholds and enantiomeric distributions of several 4-alkyl substituted gamma-lactones in Australian red wine |
Author: | Cooke, R. van Leeuwen, K. Capone, D. Gawel, R. Elsey, G. Sefton, M. |
Citation: | Journal of Agricultural and Food Chemistry, 2009; 57(6):2462-2467 |
Publisher: | Amer Chemical Soc |
Issue Date: | 2009 |
ISSN: | 0021-8561 1520-5118 |
Statement of Responsibility: | Rachel C. Cooke, Katryna A. van Leeuwen, Dimitra L. Capone, Richard Gawel, Gordon M. Elsey and Mark A. Sefton |
Abstract: | The individual enantiomers of γ-octalactone (1), γ-nonalactone (2), γ-decalactone (3) and γ-dodecalactone (4) have been synthesized. The (R) series of enantiomers was prepared from l-glutamic acid by a strategy involving deamination and reduction to (S)-5-oxo-2-tetrahydrofurancarboxaldehyde (S)-7. The different length side chains were introduced by a series of Wittig reactions, varying in the choice of phosphorane used. Hydrogenation then gave the final γ-lactones 1−4. The (S) series of enantiomers was prepared in an analogous fashion beginning with d-glutamic acid. Aroma detection thresholds for all eight enantiomers were determined in a “bag in a box” dry red wine by the application of ASTM method E 679, employing a panel of 25 members. The lowest threshold determined was 8 μg/L for (R)-dodecalactone (4) while the highest threshold was 285 μg/L for (R)-nonalactone (2). With the exception of γ-decalactone (3) there were statistically significant differences (at the 5% level) in aroma detection thresholds between the two enantiomers of the same lactone. A stable isotope method developed for quantification of the lactones 1−4 has been extended for use with chiral phase GC (Rt-βDEXcst capillary column) allowing quantification of the individual enantiomers. The enantiomeric distribution of γ-octalactone (1) and γ-nonalactone (2) in seven botrytized wines and of 2 in a total of 34 red wines were thus determined; with few exceptions, the (R) enantiomer of γ-nonalactone (2) was found to be more prevalent than its (S) counterpart in the dry red and botrytized white wines analyzed. The same was true for γ-octalactone (1) in the botrytized white wines. |
Keywords: | Lactones Alkylation Stereoisomerism Wine Australia Odorants |
DOI: | 10.1021/jf802866f |
Published version: | http://dx.doi.org/10.1021/jf802866f |
Appears in Collections: | Aurora harvest 5 Wine Science publications |
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