Synthesis of Deuterium-Labeled 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) and Quantitative Determination of TDN and Isomeric Vitispiranes in Riesling Wines by a Stable-Isotope-Dilution Assay

Abstract

The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]­dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-dilution assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography–mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).

Measurement of the Effect of Accelerated Aging on the Aromatic Compounds of Gewürztraminer and Teroldego Wines, Using a SPE-GC-MS/MS Protocol

“…The TDN mean content increased statistically significant alread 2.5 weeks, too, but was considerably more by up to 12 times, from 0.87 to 13.19 µg/L ure 3 and Table S4). Such a behavior is in accordance with the literature since the pr tion of TDN in wine is promoted by the heating [22][23][24].…”

Target-Guided Isolation of Progenitors of 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) from Riesling Wine by High-Performance Countercurrent Chromatography

“…Analytical standards were synthesized as described earlier [ 5 , 29 ]. Synthesized reference substances were purified by means of silica gel chromatography and the individual purity was checked by GC analysis and spectroscopic methods, ensuring sufficient purity for quantitative analyses.…”

“…The newly determined detection threshold was found to be 10 times lower, i.e., in the range of 2–2.3 µg/L in the wine medium. Due to global warming, TDN levels in German Rieslings are also increasing [ 5 ], and measures to reduce the risk of an off-flavor development are becoming an important issue in current oenological and viticultural research in Germany. Traditionally, Germany is the largest Riesling producer in the world and cultivates more than a third (24,000 ha) of the entire global vineyard area (64,000 ha) planted with Riesling [ 6 ].…”

Aromatypicity of Austrian Pinot Blanc Wines

“…All standards that are not commercially available were produced by self-synthesis [60,61]. The standards for the analysis of C13 norisoprenoids were received from the Technical University of Braunschweig [62].…”