Monoterpene alcohol linalool

As mentioned before, a Pseudomonas incognita was isolated by enrichment technique on the monoterpene alcohol linalool that was also able to grow on geraniol, nerol and limonene [36]. The metabolism of limonene by this bacterium was also investigated [37]. After fermentation the medium yielded as main product a crystallic acid, perillic acid, together with unmetabolised limonene, and some oxygenated compounds dihydrocarvone, carvone, carveol, p-menth-8-en-1 -ol-2-one, p-menth-8-ene-1,2-diol or p-menth-1 -ene-6,9-diol (structure not fully elucidated) and finally / -isopropenyl pimelic acid. 

As for coriander, in the unripe fruits and the vegetative parts of the plant, aliphatic aldehydes predominate in the steam-volatile oil and are responsible for the peculiar aroma. On ripening, the fruits acquire a more pleasant and sweet odour and the major constituent of the volatile oil is the monoterpene alcohol, linalool. Sotolon (also known as sotolone, caramel furanone, sugar lactone and fenugreek lactone) is a lactone and an extremely powerful aroma compound and is the major aroma and flavour component of fenugreek seeds (Mazza et al., 2002). 

Studies of the composition of the spice oil were initiated early in the 19th century and the major constituent was first isolated in 1852 by Kawalier (Purseglove et al., 1981). This compound was characterized subsequently as an alcohol and was named cori-androl in a later investigation. The identity of coriandrol was established eventually as an optically active form (dextrorotary) of the monoterpene alcohol, linalool. 

Indirect analysis of the enantiomeric ratio of an alcohol can be accomplished via separation and quantitation of the diastereomers of eq 1 by high-performance liquid chromatography (HPLC), gas-liquid chromatography (GLC), or supercritical fluid chromatography (SFC). For example, diastereomeric diacylglycerol l-(l-naphthyl)ethyl carbamates are separated by HPLC on a silica gel column, as are the diastereomeric derivatives of the tertiary monoterpene alcohol linalool, diastereomers of (unsym-... 

In addition to the enzymatic pathway of aroma formation, a thermal route also exists. At high temperatures, interactions of amino acids and sngars resnlt in the formation of various aldehydes. After thermal treatment, the tea becomes more tasty and pleasant, and has a better aroma. An essential source of secondary volatiles, formed during tea leaf processing, is oxidative. o-Quinone resulting from the oxidation of catechins can oxidize, besides amino acids and carotenes, unsaturated fatty acids as well. Linoleic and linolenic acids can be converted into hexenal and trans-hex-2-enal, respectively, and in addition, small amounts of other volatile compounds, especially hexanoic acid and trani-hex-2-enoic acid, can be formed from the same acids, respectively. Also the monoterpene alcohols, linalool and geraniol, play an important role in the formation of the aroma of black tea [38]. 

Monoterpene alcohols (Linalool, geraniol, nerol...) Vitis vinifera L. [32]... 

In the eighties, the bioconversion of monoterpene alcohols by fungi had not been studied intensively [32]. However, a strain of Aspergillus niger was isolated from garden soil, able to transform geraniol, citronellol and linalool to their respective 8-hydroxy derivatives. This reaction was called fu-hydroxylation [39,40]. 

Acyclic monoterpene alcohols are present in many essential oils and can be isolated by distillation, although nowadays, they are often synthesized from other sources. Geraniol and linalool (Fig. 7) are the most important monoterpene alcohols and together with nerol are the primary products in terpene biosynthesis [44]. a-Terpineol is a frequently used cyclic monoterpene alcohol in the fragrancing industry because of its typical lilac odor and is also partly responsible for the typical... 

Fig. 7 Monoterpene alcohols geraniol, linalool, nerol, and a-terpineol and sesquiterpene alcohols guaiol and carotol...

Essential oil recovery and composition showed variation with maturity. C. sativum L. fruits grown in Tunisia gave essential oils at the initial, middle and final stages of maturity, with yields of 0.01, 0.12 and 0.35%, respectively. Essential oil at the first stage of maturity consisted mainly of monoterpene alcohols (14.6%), especially linalool (10.96%). Other constituents were monoterpene aldehydes (2.07%), ethers, hydrocarbons and monoterpene ketones, as well as phenols and sesquiterpenes. 

Essential oil at the middle stage of maturity constituted monoterpene alcohols (76.77%), ketones (3.43%), esters (2.85%) and ethers (1.87%). Major constituents at this stage were linalool (76.3%), cis-dihydro carvone (3.21%),geranyl acetate (2.85%) and anethole (1.41%). Essential oils of mature fruit (final stage) were predominated by monoterpene alcohols (88.5%) and ketones... 

Figure 3.5 Alcohols. Linalool (3,7-dimethyl-1,6-oetadien-3-ol C]0H]80), a monoterpene alcohol. Courtesy Spiring Enterprises Ltd.

A pale yellow green liquid, its fresh, light and sharp citrus odour due to its main chemical component the monoterpene limonene (55-80%). Other mono-terpenes present are [3-pinene (10-17%), a-pinene (2.0-2.5%) and y-terpinene (3-10%). Also found in much smaller amounts are alcohol linalool (0.1-0.9%),... 

Monoterpenoids are responsible for fragrances and flavors of many plants and thus their products are used in perfumery and as spices. To date over 1,500 monoterpenoids are known, and these constitute acyclic, monocyclic, and bicyclic monoterpenoids (32), which occur in nature as hydrocarbons, alcohols, aldehydes, and carboxylic acids and their esters. Several acyclic monoterpenoid hydrocarbons are known, and these include trienes such as 3-myrcene (Cl), a-myrcene (C2), (Z)-a-ocimene (C3), ( )-a-ocimene (C4), (Z)-3-ocimene (C5), and ( )-P-ocimene (C6). 3-Myrcene and 3-ocimene are constituents of basil (Oci-mum basilicum, Labiatae) and bay (Pimenta acris, Myrtaceae), pettitgrain (Citrus vulgaris, Rutaceae) leaves, strobiles of hops (Humulus lupulus, Cannabaceae), and several other essential oils. Unsaturated acyclic monoterpene alcohol constituents of plants and their derived aldehydes play a signihcant role in the perfume industry. Some common acyclic monoterpene alcohols and aldehydes include geraniol (C7), linalool (C8) (a... 

The GC-MS and HPLC analyses of oils from Salvia sclarea provided a comparative analysis profile of different plant materials. Sesquiterpene hydrocarbons (e.g., germacrene D and (3-caryophyllene), monoterpene alcohols (e.g., ot-terpineol), diterpenoids (mainly sclareol), monoterpene hydrocarbons (e.g., myrcene, limonene, and the two ocimene isomers), and the principal components (linalyl acetate and linalool) were analyzed. 

The aroma volatiles of honeybush have also been reported by Wang et al (27). The aroma components were dominated by monoterpene alcohols, of which a-terpineol (28%) was the major component, with minor amounts of linalool (7%), nerol (2%) and geraniol (8%). These monoterpenes are responsible for the sweet, floral and fruity notes of the tea, while other components such as phenylethyl alcohol (3%) and 5-methylfurfural (2.1%) imparted also sweet and honey notes. Other volatiles such as eugenol (6%), linalool oxides (7%), and methyl-heptenol (3%) were also detected. With both honeybush and rooibos, the exact nature of the aromas and flavor will depend significantly on the species collected, time of collection, drying, fermentation and processing (27). 

Treatment of Monoterpene Alcohols. In one such series of experiments, geraniol(l), nerol (2) and linalool (3) were each heated in water at 220 °C for 10 min in the MBR. These three terpenols are practically insoluble in water at ambient temperature 10). Additionally, although they are acid labile (11-14), they do not readily react in water at moderate temperature and neutral pH. 

In the present work, geraniol (1) predominantly afforded the monoterpene alcohols a-terpineol (4) and linalool (3), along with lesser amounts of each of the hydrocarbons, myrcene (5), a-terpinene (6), limonene (7), y-terpinene (8), the ocimenes (9), a-terpinolene (10) and alloocimenes (11). The cyclic oxide, 2,6,6-trimethyl-2-vinyltetrahydropyran (12) was also present as a trace component. Nerol... 

Monoterpene alcohols Examples of these types of essential oil component are linalool, citronellol,... 

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