Green bell peppers

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. 

The mucus of the olfactory epithelimn contains odorant-hinding proteins that are specific to various odorants, such as anisole, camphor, benzalde-hyde (cherry-almond odor), 2-isobutyl-3-methoxypyrazine (green bell pepper odor), and 5o -androst-16-en-3-one (urine odor) (summarized by Leffingwell, 2001). 

Isopropyl-2-me- thoxypyrazine Green bell pepper, earthy, raw potato, miKty 0.035 [5] 0.002 in water [5]... 

However, expression in a microbial cell is not always straightforward. For example, recombinant enzyme activity maybe different from that of the native enzyme. When incubated in a mixture of hydroperoxides, a HPL from green bell pepper (Capsicum annuum L.) that was expressed in Yarrowia lipolytica favours the production of hexanal although the native enzyme produces the unsaturated aldehyde ds-3-hexenal, both within the green bell pepper itself and when expressed in E. coli [22]. 

O Strongly green (bell pepper-like) 0 0.016 ppb/water F,S 64... 

O Green (bell pepper-like), nutty 0 180 ppb/water s 64... 

F dissolved in water Allium (onion) black currant, rhubarb and green bell pepper... 

Chilli or paprika is used for flavour, not heat, in some cuisines. Flavour is a complex sensation determined in the mouth. One of the most potent volatiles known to humans is found in chilli, the pyrazine 2-methoxy-3-isobutyl-pyrazine, the green bell pepper smell. Reports indicate that humans can detect this odour at two parts per trillion. Luning et al. (1994) reported the presence of more than 80 odour compounds in C. annuum. C.frutescenscv. Tabasco contained 125 compounds whose relative abundance changed with the season of harvest. The composition of aroma compounds of Tabasco differed significantly from that of the green... 

An odor can be described by the combination of threshold value and odor quality. The threshold value, the lowest concentration that creates an odor impression, can be considered the intensity factor, whereas the odor quality describes the character of the aroma. As has been mentioned under olfactory theories, attempts at reducing the number of characteristic odor qualities to a small number have not been successful. In many cases, the aroma and flavor of a food can be related to the presence of one or a few compounds that create an impression of a particular food when smelled alone. Such compounds have been named contributory flavor compounds by Jennings and Sevenants (1964). Some such compounds are the pyrazines, which give the odor quality of green bell peppers nootkatone for grapefmit esters for fruits ... 

Three extremely odorous pyrazines, 3-isopropyl-2-methoxypyrazine, 2-s-butyl-3-methoxypyrazine, and 2-isobutyl-3-methoxypyrazine have been shown to be present in green peas, and are likely to be of major significance in the flavor of peas (59). The volatile oil of green bell peppers has been found to contain 2-isobutyl-3-methoxypyrazine as a major component (60,61). The alkylpyrazines in potato chips (62,63) and roasted peanuts (63) have been examined. 2-Isopropyl-3-methoxypyrazine has been characterized in the vacuum steam volatile oil of potatoes (64), 2-ethyl-3-methoxypyrazine in cooked potato (65), and 3-ethyl-2,5-dimethylpyrazine and 2-ethyl-3,5-dimethylpyTazine as the components important to the aroma of baked potato (66). A variety of alkylpyrazines have been identified in roasted sesame seeds (67) and 21 pyrazines have been identified in the aroma components isolated from roasted green tea (68). 

Vi red and/or green bell pepper, sliced into strips 1 to 2 tomatoes, sliced... 

CIC the typical sulphurous flavour is represented by the high concentration of dimethyl sulphide, combined with traces of 1,2-dithia-cyclo-pentene. The vegetable-green note results from 2-isopropyl-3-methoxy pyrazine, resembling raw potatoes, and 2-sec-butyl-3-methoxy pyrazine, a green bell pepper note. 

Sigge, G.O., Hansman, C.F., and Joubert, E. Optimizing the dehydration conditions of green bell peppers Capsicum Annuum L.) quality criteria, /. Food Qual., 22, 439, 1999. 

SEOW c c and lee s k (1997), Firmness and color retention in blanched green beans and green bell pepper , J Food Qual, 20, 329-336. 

Volatiles from red pepper or chills (Capsicum annuum and . frutescens) were isolated by steam distillation-solvent extraction methods. Compounds identified by gas chromatography-mass spectrometry are 17 alcohols, 20 carbonyl compounds, 14 carboxylic acids, 21 esters, 6 pyrazlnes, 14 terpene hydrocarbons, and 10 miscellaneous compounds. Only ten of these components have been reported previously in volatiles from peppers. Although the odor threshold method was applied, the characteristic red pepper odor was not fully correlated with identified constituents. The green bell pepper compound, 2-methoxy-3-lsobutylpyrazine, was found in both annuum and C. frutescens. 

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. 

Shibata, Y., Matsui, K., Kajiwara,T., Hatanaka, A. Purification and properties of fatty acid hydroperoxide lyase from green bell pepper finits. Plant Cell Physiol 36(1) (1995), 147-156... 

HPO lyase was purified to a homogeneous state from immature fruits of green bell pepper (Shibata et al 1995a). It was deduced to be a homo-trimer of 55-kDa subunits. The activity was considerably inhibited by lipophilic antioxidants such as nordihydroguaiaretic acid and a-tocopherol. Furthermore, HPO lyase was rapidly and irreversibly inactivated... 

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