Extract monoterpene hydrocarbon

Wood is the raw material of the naval stores iadustry (77). Naval stores, so named because of their importance to the wooden ships of past centuries, consist of rosin (diterpene resin acids), turpentine (monoterpene hydrocarbons), and associated chemicals derived from pine (see Terpenoids). These were obtained by wounding the tree to yield pine gum, but the high labor costs have substantially reduced this production in the United States. Another source of rosin and turpentine is through extraction of old pine stumps, but this is a nonrenewable resource and this iadustry is in decline. The most important source of naval stores is spent sulfate pulpiag Hquors from kraft pulpiag of pine. In 1995, U.S. production of rosin from all sources was estimated at under 300,000 metric tons and of turpentine at 70,000 metric tons. Distillation of tall oil provides, in addition to rosin, nearly 128,000 metric tons of tall oil fatty acids annually (78). 

Other odoriferous materials are derived from the leaves and young twigs of Cistus ladaniferus. Cistus oil is obtained by steam distillation solvent extraction yields cistus concrete. Cistus oil, in contrast to labdanum oil, consists mainly of monoterpene hydrocarbons. 

Citrus oil dominates this class of essential oil. It is obtained by the cold press method with the exception of lime oil, which is also prepared by steam distillation of essential oil separated during the production of juice.106,107 Aside from bergamot, these oils are primarily monoterpene hydrocarbon mixtures of which (if)-limonene (3) is usually the dominant compound. Since odor contribution of this monoterpene compound is low, it is often removed by distillation or repeated solvent extraction. The resulting oil rich in odor-active compounds is called terpeneless oil and is used extensively. In the case of bergamot and lemon oils, psoralen derivates like bergaptene (64) causing photosensitivity are problematic, and those for fragrance use are rectified to remove it (Table 8). 

In comparison with essential oils from conifers the enantiomeric ratio of monoterpenic hydrocarbons is more stable in citrus oils and thus it can give information about their origin, extraction techniques and genuineness of the oils. The main component of monoterpenes in those types of oils is (+)-limonene of a high enantiomeric purity for most of the citrus oils. 

Perfume materials obtained in this way are referred to as essential oils. Thus, for example, the oil obtained by steam distillation of lavender is known as the essential oil of lavender, or lavender oil. Sometimes, the monoterpene hydrocarbons are removed from the oils by distillation or solvent extraction to give a finer odour in the product. The process is known as deterpenation and the product is referred to as a terpeneless oil. This is, of course, a misnomer since, for example, the major component of lavender oil terpeneless is linalyl acetate, a monoterpene. 

Qccurance and Identification. An early report of cotton volatile composition by Minyard et al. (44) involved steam distillation of large quantities of leaves and flowers. Major compounds identified included the monoterpenes a-pinene, B-pinene, myrcene, trans-B-ocimene, and limonene ( 4). Several other monoterpene hydrocarbons were also present in low concentration. Since that report, many other terpenes have been identified in cotton essential oil steam distillates and solvent extracts. These compounds include cyclic hydrocarbons such as bisabolene, caryophyllene, copaene and humulene (45-47), the cyclic epoxide caryophyllene oxide (45), cyclic alcohols such as bisabolol, spathulenol, and the aromatic compound... 

C. consist mainly of monoterpene hydrocarbons, above all limonene (see p-menthadienes) (exception bergamot oil, that only contains ca. 40%). Since the important odor and taste components are thus only present in relatively low concentrations, so-called concentrates of C. are produced, especially for use as aromatizing agents, by removing a large portion of the unwanted non-polar terpene hydrocarbons, thereby the content of the polar components is increased. This can be achieved technically by distillation, distribution, extraction, or adsorption processes. 

Holm, Y. Vuorela, P. Hiltunen, R. (1997). Enantiomeric composition of monoterpene hydrocarbons in n-hexane extracts of Angelica archangelica L. roots and seeds. Flavour and Fragrance Journal, Vol.l2, N0.6, (November/December 1997), pp. 397-400, ISSN 1099-1026... 

The secretion of the East African species A. messinae contains the eudesmane but the minor component is limonene (Meinwald etal., 1978). Of two sympatric species, A. unidentatus produces mainly methyl ketones, principally 2-tridecanone, and A. lonnbergianus has no hexane-extractable material. The North American species, A. wheeleriproduces a sesquiterpene hydrocarbon only (Prestwich, 1979b), while the Australian species, A. herbertensis and A. laur-contain monoterpene hydrocarbons, the former terpinolene (>98%) and a-phellendrene and the latter limonene and -pinene (Moore, 1968). 

More recently, supercrilical COj has been used for this purpose. Extraction may be carried out at low temperature (O to 10°C) and high pressure (8-80 atm). Under these conditions CO2 hquefies to become a nonpolar selective solvent, which is odorless, tasteless, colorless, easily ranoved without residues and is nonflammable. Capital investment in the plant is high, but the extraction is claimed to be more effective with the added advantage that there are no solvent residues, no off-odors, low monoterpene hydrocarbon levels, more top-notes and more back-notes giving a fuller but different profile than with traditional extraction methods [20-25]. The higher cost and different flavor profile obtained with supercritical CO2 has limited the use of this technique despite its inherent advantages. 

A yield of 18.5% has been reported for L.CC>2 extraction at 60 bar and 20°C [16]. This yield is variable and dependant on the batch of spice, and it is possible to extract up to 50% of low molecular weight lipids [161]. The composition of a typical L.CO2 extract is 38% monoterpene hydrocarbons, 6.1% elemicin + myristicin, with desirably low levels of only 0.8% para-cymene and 0.1% alpha terpineol. 

The chemistry of thyme oil has been reviewed [219-223]. A gc-ms study of laboratory extracted L.CO2 and steam-distilled red thyme oil prepared from the same lot of leaves was reported by Bestman [224]. Of significant difference in composition of the two oils were, lower monoterpene hydrocarbons especially para-cymene and higher levels of free fatty acids Cig-Cig in the CO2 extract. 

In pine needles, the enzymes present in 100,000 g supernatants were able to synthesize sesquiterpene and diterpene hydrocarbons from [1- C] IPP whereas the synthesis of monoterpene hydrocarbons was never observed. However, it appeared that the enzymes, extracted from needles originating from Landes area, were able to convert IPP into sesquiterpene hydrocarbons with small amounts of diterpenes. In contrast, the enzymes from needles of maritime pines from Corsican origin used IPP to form mainly diterpene hydrocarbons with small amounts of C compounds. The diluted proteins extracted from 100,000 g supernatants obtained from needles of Corsican pines, were also precipitated with PEG 6000 (30- 0%). After purification by ion exchange column chromatography developed with a NaCl step gradient (0.1, 0.2, 0.3 M), an enzyme system, able to carry out all the steps leading to C, and C Q hydrocarbons from [1- C] IPP, was obtained at 0.2 M NaCl (fig. 2). r H]-GGPP was also used by this enzyme complex and was cyclised into diterpene hydrocarbons, mainly 7,13-abietadiene (Walter, unpublished data). This complex was... 

Table I shows the quantitative comparison of selective compounds in the hydrocarbon fraction. The total amount of monoterpenes in the steam distilled sample was less than that in the liquid carbon dioxide extract. These compounds could have been lost during distillation. The significant decrease in zingiberene and the concomitant increase in ar-curcumene confirmed that zingiberene was converted to ar-curcumene (16). g-Sesquiphelladrene, another compound which could be converted to ar-curcumene, decreased slightly. The scheme of oxidative conversion of zingiberene and B-sesquiphel-...

Recently, the chemistry of total extracts of another species of Gynaikothrips was examined (17). G. uzeli is reported to produce the same hydrocarbons and acetates as G. ficorum, but in addition synthesizes a novel monoterpene, p-acaridial, a compound recently identified as a natural product of a mite (j ). p-Acaridial has also been identified as an important compound produced by two other species of thrips, Varshneyia pasanii and Liothrips kuwanai (17). The function of p-acaridial, which is very unstable, is not known. 

The volatile fractions of many plants are isolated by steam distillation, distillation, or by solvent extraction (Banthorpe, 1991). The resulting volatile compounds that make up the essence or aroma of plants are called essential oils. Altiiough essential oils are comprised of many types of compounds, monoterpenes are major among them. These oils may also contain metabolically modified fatty acids, aldehydes, hydrocarbons, esters, phenylpropanoid compounds, acetylenic compounds, volatile alcohols, volatile alkaloids, phenylpro-panoids, and other shikimic acid derivatives. 

The most important natural sources of flavors are the essential oils derived from spices, fruits, and flowers as well as extractives and exudates (resins) from certain plant sources and animal secretions, e.g., musk. Essential oils are aromatic substances which are widely used in several industries such as perfume, pharmaceutical, food, and nutrition. These are mixtures of more than 200 compounds [14,16]. It contains monoterpenes, sesquiterpene hydrocarbons, and their oxygenated derivatives, along with aliphatic and aromatic aldehydes, alcohols, esters, and nonvolatile residues. Generally, terpenes are unsaturated com-... 

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