DETERMINATION OF METHOXYPYRAZINES IN RED WINES BY STABLE-ISOTOPE DILUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Quantitative analysis of methoxypyrazines in a range of red wines is r eported for the first time. By stable isotope dilution gas chromatogra phy-mass spectrometry, 2-methoxy-3-(2-methylpropyl) pyrazine was deter mined in 12 Australian and New Zealand Cabernet Sauvignon wines (mean concentration, 19.4 ng/L) and in 6 Bordeaux wines that are blends, to varying degrees, of Cabernet Sauvignon, Merlot, and Cabernet Franc (me an concentration, 9.8 ng/L). These findings suggest that the concentra tion of the methoxypyrazine in wines of these varieties is ca. 30 time s lower than that indicated in a previous study. In these 18 wines, th e concentration of the methoxypyrazine exceeded its sensory detection threshold in water, consistent with its contributing to wine flavor. T he concentration two French Pinot noir wines was below the sensory det ection threshold. In all wines, the level of 2-methoxy-3-(1-methylprop yl)pyrazine was less than 2 ng/L.