2-Acetyl-3-methoxypyrazine

More than 100 different pyrazines have been identified in various food products. The sensory properties of the pyrazines are quite diverse. The alkyl pyrazines (Figure 5.5a) generally possess roasted, nut-like notes while methoxypyrazines (Figure 5.5b) often possess earthy, vegetable notes [47]. The 2-isobutyl-3-methoxy pyrazine has a freshly cut green pepper flavor with a sensory threshold of 0.002 ppb in water. The acetyl pyrazines typically have a popcorn character, and 2-acetonyl pyrazine has a... 

One must recognize that microorganisms can accomplish a wide range of chemical transformations thereby potentially producing a host of different oflf-flavors. Earlier in this section, several oflf-notes have been described as being the result of microbes. One can add other sensory notes such as faceal (indole and skatole in rotting potatoes [147]), musty potato (2-methoxy-3-isopropylpyrazine [148]), mousy (wine, 2-acetyl-1,4,5,6-tetrahydropyridine [149]), and musty, dirty dishcloth (machine oils 2,6-dimethyl-3-methoxypyrazine [150]). 

Fig. 5.8. FD chromatogram of the volatile fraction of French fries. Ordinate n, number of 1 + 1 dilutions. Abscissa retention index (RI) on the capillary SE-54. The following odorants were identified 1 methional, 2 2-acetyl-1-pyrroline, 3 dimethyltrisulfide, 4 l-octen-3-one, 5 phenylacetaldehyde, 6 2-ethyl-3,6-dimethyl-pyrazine, 7 2-ethyl-3,5-dimethylpyrazine, 8 nonanal, 9 (Z)-2-nonenal, 10 2,3-diethyl-5-methylpyrazine, 11 (E)-2-nonenal, 12 2-ethenyl-3-ethyl-5-methylpyrazine, 13 2-isobutyl-3-methoxypyrazine, 14 dimethyltetrasulfide, 15 (E,E)-2,4-nonadienal, 16 (Z)-2-decenal, 17 (E,Z)-2,4-decadienal, 75 (E,E)-2,4-decadienal, 79trans-4,5-epoxy-(E)-2-decenal (according to Wagner and Grosch, 1997)...

The compounds (Z)-3-hexenal, methanethiol, (Z)-l,5-octadien-3-one, dimethyltrisulfide, 3-iso-propyl-2-methoxypyrazine and 3-5 c-butyl-2-methoxypyrazine contribute to the aroma of the fresh vegetable. In cooked spinach, (Z)-3-hexenal decreases and dimethylsulfide, methanethiol, methional and 2-acetyl-1-pyrroline are dominant. 

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