| Abstract
| - A stable isotope dilution assay has been developed for quantification of (E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene (4) in wine using a [2H6]-analogue. Using this method, 4 was found in 96 out of 97white wines, but in none of 12 red wines analyzed. 4 was found to be most prevalent in Semillonwines, followed by Chardonnay, with Riesling showing the least amount of 4 among these threevarieties. 4, like 1,1,6-trimethyldihydronaphthalene (TDN, 3), appears to be formed during the agingprocess. 4 was found to be unstable in model wine, and in both white and red wine, with the orderof stability being model > white > red. In a PVPP-stripped red wine, the rate of degradation of 4 wassubstantially lessened, with the final concentrations very close to those observed in model wine.When treated with either grape or wine tannin extracts in model wine, the concentration of 4 wasfound to decrease to levels very close to those observed with an untreated red wine. When whitewine was heated at 45 °C, 4 was formed, indicating the presence of precursor forms. The amountsformed were much higher than those found in a commercial white wine. 4 was also observed in redwine heated to 45 °C, but the concentration produced was much less than that with white wine. Keywords: TPB; SIDA; polyphenols; grapes; precursors; C13-norisoprenoids
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