Methoxypyrazines are a class of chemical compounds that produce odors. The odors tend to be undesirable, as in the case of certain wines,
/ref> or as defensive chemicals used by insects such as ''Harmonia axyridis
''Harmonia axyridis'' is a large lady beetle or ladybug species that is most commonly known as the harlequin, Asian, or multicoloured Asian lady beetle. This is one of the most variable lady beetle species in the world, with an exceptionally wid ...
'' which produces isopropyl methoxy pyrazine
Isopropyl methoxypyrazine (IPMP) is a methoxypyrazine, a class of chemical compounds that produce odors. The odor is rather undesirable and is produced by the Asian lady beetle or by the actinomycete '' Streptomyces'' sp. It can be detected by h ...
(IPMP). They have also been identified as additives in cigarette manufacture. Detection thresholds are very low, typically near 2 parts per trillion (1 ng/L).
Examples of methoxypyrazines in wine grapes
Cabernet Sauvignon
Cabernet Sauvignon () is one of the world's most widely recognized red wine grape varieties. It is grown in nearly every major wine producing country among a diverse spectrum of climates from Australia and British Columbia, Canada to Lebano ...
has high levels of methoxypyrazines.[Oz Clarke ''Encyclopedia of Grapes'' pg 223 Harcourt Books 2001 ] Two methoxypyrazine compounds, 3-isobutyl-2-methoxypyrazine
3-Isobutyl-2-methoxypyrazine (2-isobutyl-3-methoxypyrazine also known as Grindstaff pyrazine) is a methoxypyrazine that is very similar to isopropyl methoxy pyrazine except that the alkyl side-group contains an isobutyl group attached to the carbo ...
(IBMP) and 3-isopropyl-2-methoxypyrazine
Isopropyl methoxypyrazine (IPMP) is a methoxypyrazine, a class of chemical compounds that produce odors. The odor is rather undesirable and is produced by the Asian lady beetle or by the actinomycete '' Streptomyces'' sp. It can be detected by ...
(IPMP), are considered to be important determinants of "green" (i.e., herbal, grassy, or vegetal) flavours in Sauvignon blanc
Sauvignon blanc () is a green-skinned grape variety that originates from the city of Bordeaux in France. The grape most likely gets its name from the French words ''sauvage'' ("wild") and ''blanc'' ("white") due to its early origins as an ind ...
wines.[Marais, J., Hunter, J.J., & Haasbroek, P.D. (1999). Effect of microclimate, season and region on Sauvignon blanc grape composition and wine quality. South African Journal of Enology and Viticulture, 20, 19-30.]
See also
* Alkylpyrazine Alkylpyrazines are chemical compounds based on pyrazine with different substitution patterns. Some alkylpyrazines are naturally occurring highly Aroma compound, aromatic substances which often have a very low odor threshold and contribute to the ta ...
s
References
{{reflist
Pyrazines
Ethers
Wine chemistry