METHOXYPYRAZINES IN RED WINES - OCCURRENCE OF 2-METHOXY-3-(1-METHYLETHYL)PYRAZINE

Methoxypyrazine quantitative analysis by stable isotope dilution gas chromatography-mass spectrometry has identified a wine in which the concentration of 2-methoxy-3-(1-methylethyl)pyrazine (isopropylmethoxypyrazine) in one bottle (9.7 ng/L) was comparable with the concentration of 2-methoxy-3-(2-methylpropyl)pyrazine (isobutylmethoxypyrazine) (9.3 ng/L). At this concentration, sensory detection threshold data suggest that isopropylmethoxypyrazine may contribute to the aroma of the wine more strongly than isobutylmethoxypyrazine. Comparatively low levels of isopropylmethoxypyrazine were found in other wines studied and in other bottles of the same wine. This suggests that isopropylmethoxypyrazine can occur in wine from sources other than the grape berry and normal winemaking processes.