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

Methoxypyrazine quantitative analysis by stable isotope dilution gas c hromatography-mass spectrometry has identified a wine in which the con centration of 2-methoxy-3-(1-methylethyl)pyrazine (isopropylmethoxypyr azine) 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 sugges t that isopropylmethoxypyrazine may contribute to the aroma of the win e 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 isopropylmethoxypyr azine can occur in wine from sources other than the grape berry and no rmal winemaking processes.