Methoxy-3-isobutylpyrazine

As well as a number of monoterpenoids and compounds from other classes, one major component of the characteristic pleasant aroma of green bell peppers. Capsicum annuum L. var. grossum, was identified as 2-methoxy-3-isobutylpyrazine (Fig. 5.1) (Buttery et al. 1969). Afterwards, this metabolite also turned out to be a constituent of further vegetables from different plant families. 

Eckart Eich, Solanaceae and Convolvulaceae Secondary Metabolites Springer-Verlag Berlin Heidelberg 2008 

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Another commercially available compound which is important to the galbanum aroma is 2-methoxy-3-isobutylpyrazine [24683-00-9] (48), which possesses an intense green pepper odor. 

Flavor 2-methoxy-3-isobutylpyrazine increase p-carotene. other carotenoids. 

Although most consumers appreciate the fieriness of chile, capsaicinoids are not perceived through odor or taste receptors but through the nociceptive pain receptors described earlier. The compounds in chile fruit that create the flavor and aroma are produced in the fruit wall. Buttery et al. [90] generated vacuum steam distilled oil from green bell pepper macerate, with well over 40 peaks on subsequent GC/MS analysis. Of these peaks, the major flavor compound associated with bell pepper aroma was 2-methoxy-3-isobutylpyrazine (Fig. 8.1). They also reported several monoterpenoids in abundance, limonene, trans- 3-ocimene, and linalool as well as other aliphatic aldehydes and ketones. The flavor composition of dried red bell pepper powder (sweet paprika) extracted with ether identified 44 key peaks by GC/MS [91]. In these dried samples the key compounds were P-ionone and several furanones. The post-harvest processing and the different fruit maturities as well as possible varietal differences are all causes for the different aromatic profiles. 

Methoxy-3-isobutylpyrazine 176 (Structure 4.53) is found in galbanum oil obtained from Ferula galbaniflua. 2,4-disubstituted pyridines 177, N,N-dimeth-ylated amino compounds 178, alkyl pyrazines 179, quinoline 180 and methyl quinolines 181 were isolated from fig leaf absolute [64]. 

The concentration of 2-methoxy-3-isobutylpyrazine varies in roasted coffee from 10 to 50 ppb and is therefore a compound with a high flavor value (> 1000 F.U.) in roasted coffee. Nitz et al. (2S ) demonstrated that the "peasy" off-flavor in certain African coffee beens is caused by a 5 to 20 fold increase of 2-methoxy-3-iso-propylpyrazine, obviously formed by fungi. 

Kotseiidis, Y, Baumes, R., Skouroumounis, G. K. (1998). Synthesis of labelled pH4]-(3-damascenone, pH2]-2-methoxy-3-isobutylpyrazine, pH2]-ct-ionone, and pH3]-(3-ionone, for quantification in grapes, juices and wines. J. Chromatogr. A, 824, 71-78. 

Chapman, D.M., Thomgate, J.H., Matthews, M.A., Guinard, J.X., and Ebeler, S.E. (2004). Yield effects on 2-methoxy-3-isobutylpyrazine concentration in Cabernet Sauvignon using a solid phase microextraction gas chromatography/mass spectrometry method. J. Agric. Food Chem., 52, 5431-5435. 

Falcao, L.D., de Revel, G., Perello, M.C., Moutsiou, A., Zanus, M.C., and Bordignon-Luiz, M.T (2007). A survey of seasonal temperatures and vineyard altitude influences on 2-methoxy-3-isobutylpyrazine, C-13-norisoprenoids, and the sensory profile of Brazilian Cabernet Sauvignon wines. J. Agric. Food Chem., 55, 3605-3612. 

Kotseridis, Y, Baumes, R.L., Bertrand, A., and Skouroumounis, G.K. (1999). Quantitative determination of 2-methoxy-3-isobutylpyrazine in red wines and grapes of Bordeaux using a stable isotope dilution assay. J. Chromatogr. A., 841, 229-237. 

Main components Sharp tasting capsaicinoids (0.3-0.5%) these are vanillyl amides of various acids, whereby capsaicin, the vanillyl amide of an isodecenylic acid, is most important. Furthermore, dihydro-, nordihydro-, homo- and homodihydrocapsai-cin and others have been found [234], Sugar (up to 50%), ascorbic acid, traces of essential oil with 2-methoxy-3-isobutylpyrazine as main aroma constituent [235, 236, 237], A steroid saponin mixture, called capsicidin which functions antibacterially against yeast fungi [238], 0.3-0.8% carotenoids, partly esterified with fatty acids (mainly capsanthin, its isomer capsombin and a-carotene). 

Roujou de Boubee, D., Van Leeuwen, C., and Dubourdieu, D. (2000). Organoleptic impact of 2-methoxy-3-isobutylpyrazine on red Bordeaux and Loire wines. Effect of environmental conditions on concentrations in grapes during ripening, J. Agric. Food Chem., 48(10), 4830-4834. 

Methoxy-3 -isobutylpyrazine 2-Methoxy-3 -isopropylpyrazine 2-Methoxy-3 -sec-butylpyrazine... 

Fig. 7.7. Correlation between the green pepper character identified on tasting and the concentration of 2-methoxy-3-isobutylpyrazine (IBMP) in various red Bordeaux wines (Roujou de Boubee, 1996)...

Concentrations of 2-methoxy-3-isopropylpyra-zine and 2-methoxy-3- ec-butylpyrazine in Sauvignon Blanc and Cabernet Sauvignon wines are systematically lower than those of 2-methoxy-3-isobutylpyrazine. They have no influence on taste. 

Methoxy-3-isobutylpyrazine. See 2-lsobutyl-3-methoxy-pyrazine Methoxyisopropanol CAS 107-98-2 EINECS/ELINCS 203-539-1 UN 1993 3092 (DOT)... 

Bayonove C, Cordonnier R, Dubois P (1975) Etude d une fraction caracteristique de Tarome du raisin de la variete Cabernet-Sauvignon mise en evidence de la 2-methoxy-3-isobutylpyrazine. C R Acad Sci Paris Ser D 281 75-78... 

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