Abstract
Changes in several physicochemical parameters of grape composition including pH, titratable acidity, soluble solids, weight, color, and phenolic content were examined for Gewürztraminer during ripening. Free and potentially volatile terpenes obtained by distillation were also assessed spectrophotometrically using an acidified vanillin assay and by gas chromatography-mass spectrometry (GC-MS). The colorimetric values of potentially volatile terpenes were estimated to account for nearly 84% of the bound terpenes, and the values of the free volatile terpenes reflected primarily the content of unsaturated aldehydes rather than the free terpenes. A procedure using selected ions specific to terpenes was developed to accelerate the analysis time of GC-MS chromatograms. Based on selected ion chromatograms, higher correlations were found for the bound terpene concentrations in Gewürztraminer vis-à-vis total skin phenolics, skin anthocyanins, and the traditional maturity indices of soluble solids and titratable acidity as compared to free terpene content.
- Gewürztraminer
- grapes
- Vitis vinifera
- free terpenes
- bound terpenes
- volatiles
- flavor
- phenolic content
- composition
Acknowledgments: The financial support of the Science Council of British Columbia is gratefully acknowledged. The authors also thank Tom Kopp for technical assistance.
- Copyright 2002 by the American Society for Enology and Viticulture
Sign in for ASEV members
ASEV Members, please sign in at ASEV to access the journal online.
Sign in for Institutional and Non-member Subscribers
Log in using your username and password
Pay Per Article - You may access this article (from the computer you are currently using) for 2 day for US$10.00
Regain Access - You can regain access to a recent Pay per Article purchase if your access period has not yet expired.