Natural green notes

LOX is an important factor in the large-scale use of plant enzymes for the production of natural green note aroma compounds, a group of isomeric C6 aldehydes and alcohols [66]. 

In nature, the green notes are produced after the destruction of the plants tissue (leaves, fruits or vegetables). Destruction of the cell wall leads to a cascade of enzyme-catalysed reactions polyunsaturated fatty acids with the diene system described before are converted into hydroperoxides by LOX catalysis. The hydroperoxide lyase cleaves the hydroperoxides in the whole cascade, oxireduc-tases are involved too. The biotechnological large-scale production of natural green notes follows the natural pathway. 

Whitehead, I.M., Muller, B.L., and Dean, C., Industrial use of soybean lipoxygenase for the production of natural green note flavor compounds, Cereal Foods World, 40, 193, 1995. 

In this system, surprisingly only (E)-2 hexenol was oxidized. Thus this observation was applied to developing natural green notes. The natural C6 alcohols mixture used was composed of (E)-2-hexenol, (Z)-3-hexenol and hexanol and was isolated as the top fraction of mint oils from distillation. In terms of green note, (E)-2-hexenol is less valuable. On other hand, its aldehyde form (E)-2-hexenal is quite an important component of green notes. Figure 4 shows Candida boidinii SA051 could selectively oxidize (E)-2-hexenol in the mixture to desirable (E)-2-hexenal. 

The production processes of natural green notes based on plant homogenates as enzyme sources are cheap, but they are limited by low enzyme concentration and specificity. Recombinant enzymes expressed in yeast or bacteria showed some promise, because they are characterized by very specific enzyme activities, and they avoid the generation of high amounts of biomass. 

Leaf alcohol is used to obtain natural green top notes in perfumes and flavors. In addition, it is the starting material for the synthesis of 2-/rans-6-cw-nonadien-l-ol and 2-trans-6-cis-nona6 Qn-1 -al. 

Coumarin 162 (Structure 4.49) is a naturally occurring lactone in crystal form found in hay and tonka beans. It is one of the most used fragrance materials and is responsible for spicy green notes. Dihydrocoumarine 163 is also present in various essential oils with a characteristic sweet herbal odour. Umbellif-erone 164, scopoletin 165, bergaptene 166 and coumarin are found in Rutaceae, Apiaceae, Lamiaceae and Asteraceae oils. Nepetalactones 167 are confined to the oils of Nepeta species [1,3, 21-23, 63]. 

Elderberry (Sambucus nigra) is cultivated on small scale in Europe. The fruits have a high concentration of red and purple anthocyanins and a relatively low concentration of sugars, organic acids and aroma compounds, which make this juice attractive as a natural colour ingredient in other red fruit products [126-129]. The fresh green odour of elderberry juice is associated with volatile compounds with typical green notes such as 1-hexanol, 1-octanol, (Z)-3-hexen-l-ol, ( )-2-hexen-l-ol, hexanal and ( )-2-hexenal, whereas the floral aroma is mainly due to the presence of hotrienol and nonanal [127-130]. 

Green notes are some of the most important in perfumery, finding their way into almost every type of perfume. But because of their frequent strength they are also some of the most difficult to use. Of the natural products available to the perfumer, galbanum is of out-... 

The green note of Fidji is one of exceptional complexity. By using a great many individual materials, in trace amounts, a naturalness can in fact be achieved in which no one "chemical" note predominates. In all probability, these materials are added in the form of several subcompounds or bases, including a hyacinth and a narcisse. Natural narcisse and violet leaf may also be used. 

Hedione, cA-3-hexenyl salicylate, and benzyl salicylate (6%) are again important, with Galaxolide (5%) introduced as part of the musk complex in conjunction with musk ketone, cyclopentadecanolide, and Tonalid. It is common practice among perfumers today to use a combination of synthetic musk materials, usually of chemically different types, rather than just one. As with the green notes this complexity gives a more natural and interesting effect. 

Due to its high commercial value the flavour of apples belongs to the best known and documented natural flavours. Many hundreds of varieties have been bred and are produced throughout the world. Therefore, each person has its preferred and typical apple flavour a juicy, refreshing, sweet-acid, watery taste is combined with fruity, estery, green notes, supported by species characterizing sweet, floral impressions. 

These often have very powerful odours (Boelens and Gemert, 1994) for example, 2-isobutyl-3-methoxypyrazine from galbanum oil has a powerful green note and l-para-menthene-8-thiol, a very powerful natural material, has a strong grapefruit odour at concentrations in the p.p.b. range. 

CnHisCK Mr 194.28, does not occur in nature. It is a colorless liquid, df 0.954-0.962, Up 1.478-1.483, with powerful leafy-green, nasturtium, and hyacinth note. It can be synthesized by reaction of a 1 1 molar ratio of ethyl vinyl ether and phen-ethyl alcohol in the presence of cation exchange resin [141]. It imparts fresh, floral, green notes and is used in fine fragrances as well as in soap, cosmetics and detergents. 

The odor of the (E.EHsomer is extremely powerful, orange-like, sweet and fresh-citrusy, diffusive, yet quite tenacious. The orange character is more attractive and natural at dilutions below 0.1 %, while higher concentrations display fatty-green notes (Arctander, 1967). For Ullrich and Grosch (1987) the odor description was deep fried and for Holscher et al (1990) it is fried, oily. The flavor is meaty, cereal (Chemisis, 1973). 

Another example is the production of green note compounds using lipoxygenase pathway enzymes. Lipoxygenase and hydroperoxide lyase are the determinant enzymes for the conversion of fatty acids into natural food flavor components. However, these compounds present in natural sources at very low levels and because of their instable nature it has been difficult to purify these compounds. As a result, considerable efforts have been made to clone these two enzymes for commercial uses in the production of natural flavor components. Many plant lipoxygenase from different plants have been cloned and expressed in E. coli or yeast [5],... 

Aldehydes and the related alcohols are produced by the action of hydroperoxide lyases, isomerases, and dehydrogenases. Many of the natural aromas of fruits and vegetables responsible for their green notes , such as hexanal, hexanol, 2-(E)-hexenal, and 3-(Z)-hexenol, are carbon compounds formed through this pathway. 

Besides naturally occurring cyclic monoolefins, also synthetic analogs were screened. A typical example is cyclooctene (Scheme 6.16). Reaction of syngas with this cycloolefin in the presence of an unmodified Co catalyst under unusually smooth conditions in a >200 g scale gave cyclooctane carbaldehyde [87]. The product was converted into the corresponding acetals, a modification that enhances the intensive green note of the precursor aldehyde. Alternatively,... 

The first report concerning barium compounds occurred in the early part of the seventeenth century when it was noted that the ignition of heavy spar gave a peculiar green light. A century later, Scheele reported that a precipitate formed when sulfuric acid was added to a solution of barium salts. The presence of natural barium carbonate, witherite [14941-39-0] BaCO, was noted in Scodand by Withering. 

Other Color Order Systems. The Natural Color System (24), abbreviated NCS, developed ia Sweden is an outgrowth of the Hesselgren Color Adas, and uses the opponent color approach. Here colors are described on the basis of their resemblances to the basic color pairs red-green and blue-yeUow, and the amounts of black and white present, all evaluated as percentages. Consider a color that has 10% whiteness, 50% blackness, 20% yellowness, and 20% redness note that the sum is 100%. The overall NCS designation of this color is 50, 40, Y50R iadicating ia sequence the blackness, the chromaticness (20 + 20), and the hue (50% on the way from yellow to red the sequence used is Y, R, G, B, Y). 

Natural products have been noted for their potential health benefits from time immemorial and are the basis of Ayurveda, an ancient Indian medical practice (Bushkin and Bushkin, 2002). However, the potential benefits of several natural products reside in one or two active ingredients. For example green tea stands for polyphenols, soy for soy estrogens, broccoli for isothiocyanates and grape seed for polyphenols. The beauty of rice bran is that there are more than 100 antioxidants, several categories of bioactive phytonutrients, such as IP6, polyphenols, phytosterols, tocotrienols, y-oryzanol, B vitamins, minerals and trace minerals in addition to fat, protein, fiber, polysaccharides and other nutrients. These phytonutrients and antioxidants of rice bran are believed to act at the cellular level, and their synergestic function is responsible for the positive health benefits. 

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