Quantification of Polyfunctional Thiols in Wine by HS-SPME-GC-MS Following Extractive AlkylationReportar como inadecuado




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1

Department of Food Science, Cornell University, Stocking Hall, 411 Tower Road, Ithaca, NY 14853, USA

2

E. & J. Gallo Winery, 600 Yosemite Boulevard, Modesto, CA 95354, USA





*

Author to whom correspondence should be addressed.



Academic Editors: Susan Ebeler and Helene Hopfer

Abstract Analyses of key odorous polyfunctional volatile thiols in wines 3-mercaptohexanol 3-MH, 3-mercaptohexylacetate 3-MHA, and 4-mercapto-4-methyl-2-pentanone 4-MMP are challenging due to their high reactivity and ultra-trace concentrations, especially when using conventional gas-chromatography electron impact mass spectrometry GC-EI-MS. We describe a method in which thiols are converted to pentafluorobenzyl PFB derivatives by extractive alkylation and the organic layer is evaporated prior to headspace solid phase microextraction HS-SPME and GC-EI-MS analysis. Optimal parameters were determined by response surface area modeling. The addition of NaCl solution to the dried SPME vials prior to extraction resulted in up to less than fivefold improvement in detection limits. Using 40 mL wine samples, limits of detection for 4-MMP, 3-MH, and 3-MHA were 0.9 ng-L, 1 ng-L, and 17 ng-L, respectively. Good recovery 90%–109% and precision 5%–11% RSD were achieved in wine matrices. The new method was used to survey polyfunctional thiol concentrations in 61 commercial California and New York State wines produced from V. vinifera Riesling, Gewürztraminer, Cabernet Sauvignon, Sauvignon blanc and non-varietal rosé wines, V. labruscana Niagara, and Vitis spp. Cayuga White. Mean 4-MMP concentrations in New York Niagara 17 ng-L were not significantly different from concentrations in Sauvignon blanc, but were significantly higher than 4-MMP in other varietal wines. View Full-Text

Keywords: wine; polyfunctional thiols; extractive alkylation; Vitis labruscana wine; polyfunctional thiols; extractive alkylation; Vitis labruscana





Autor: Lauren E. Musumeci 1, Imelda Ryona 1, Bruce S. Pan 2, Natalia Loscos 2, Hui Feng 2, Michael T. Cleary 2 and Gavin L. Sacks 1,*

Fuente: http://mdpi.com/



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