Monoterpenes pressings

Figure 10.3 Gas cliromatograms of a cold-pressed lemon oil obtained (a) with an SE-52 column in the stand-by position and (b) with the same column showing the five heart-cuts (c) shows the GC-GC chiral chromatogram of the ti ansfeired components. The asterisks in (b) indicate electric spikes coming from the valve switcliing. The conditions were as follows SE-52 pre-column, 30 m, 0.32 mm i.d., 0.40 - 0.45 p.m film tliickness cairier gas He, 90 KPa (stand-by position) and 170 KPa (cut position) oven temperature, 45 °C (6 min)-240 °C at 2 °C/min diethyl-tert-butyl-/3-cyclodextrin column, 25 m X 0.25 mm i.d., 0.25 p.m film thickness cairier gas He, 110 KPa (stand-by position) and 5 KPa (cut position) oven temperature, 45 °C (6 min), rising to 90 °C (10 min) at 2 °C/min, and then to 230 °C at 2 °C/min. Reprinted from Journal of High Resolution Chromatography, 22, L. Mondello et al, Multidimensional capillary GC-GC for the analysis of real complex samples. Part IV. Enantiomeric distribution of monoterpene hydrocarbons and monoterpene alcohols of lemon oils , pp. 350-356, 1999, with permission from Wiley-VCH.

L. Mondello, M. Catalfamo, R Dugo and G. Dugo, Multidimensional capillary GC-GC for the analysis of real complex samples. Part II. Enantiomeric distr ibution of monoter-pene hydrocarbons and monoterpene alcohols of cold-pressed and distilled lime oils , 7. Microcolumn Sep. 10 203-212 (1998). 

Nelson SD, McClanahan RH, Knebel N, Xhomassen D, Gordon WP, Doshi S, Xhe metabolism of (A)-(+)-pulegone, a toxic monoterpene, in Petrosky RJ, McCormick SP (eds.), Secondary-Metabolite Biosynthesis and Metabolism, Plenum Press, New York, USA, 1992. 

Gershenzon, J. and Croteau, R. (1993). Terpenoid biosynthesis the basic pathway and formation of monoterpenes, sesquiterpenes and diterpenes. In Lipid Metabolism in Plants, ed. T. S. Moore Jr, pp. 339-388. Boca Raton, FL CRC Press. 

Cold pressed orange oil contains over 95 by weight monoterpene hydrocarbons. The principal constituent, d-limonene, ranges from 83-97 percent (9), Limonene degradation has been well docu-meted in the literature (LO, 1 1). Anandaraman identified limonene-1,2-epoxide and carvone as two of the earliest degradation products of d-limonene (12, 13). 

Wilson, C.W. and Shaw, P.E. 1981. Importance of thymol, methyl V-methylanthranilate and monoterpene hydrocarbons to the aroma and flavor of mandarin cold-pressed oils. J. Agric. Food Chem. 29 494-496. 

SUMMARY In essential oils, most constituents are terpenes and terpenoid molecules. The method of extraction can influence the terpene content. In citrus oils extracted by expression (squeezing or pressing the plant material), the terpenes present are similar to those found in the living plant tissue for example, orange, lemon, mandarin and grapefruit essential oils may be made up of up to 90% of the monoterpene limonene. When extraction is by steam distillation the action of the hot water and steam on thermolabile (heat-sensitive) molecules present in the plant is responsible for the formation of the bulk of the terpene content. Solvent extraction often produces absolutes that are very low in terpenes or do not contain them at all, when compared to a distillation of the same material, for example as found in lavender and rose products. 

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). 

The distribution of monoterpenes among separate fractions of the grape. As a prerequisite to any biosynthetic studies on terpenes in grapes the sites of production and storage within the berry must be known. Such knowledge may have considerable practical consequences by providing valuable guidance in the application of skin contact and press conditions to optimize flavorants in juice. 

Effect of pressings on monoterpene composition of musts and wines. 

Kinzer and Schreier (77) found that, compared with free run juice, pressings contained higher concentrations of monoterpene alcohols. When a pressing aid was used, wines made from the juice contained 34-38% less monoterpenes than wines produced from the same system without pressing aid. Bayonove et al. (78,79) also studied effects of pressing and of skin contact in muscat musts. 

Each datum represents the weight fraction of oil from one of the 3 different types of oranges two from Brazil and one from Greece. Cold-pressed and dewaxed oils were used as feed material that has average monoterpene of about 98.5 wt%, including D-Limonene about 95.3 wt%. 

Monoterpenes, on the other hand, possess particularly desirable flavor notes. Three of them, (3-myreene (A.45), limonene (A.46) and p-cymene (A.59) are common to coffee, cocoa and tea, and to numerous plant families (3-myrcene for example constitutes 63% of hop oils. It is worth remembering that they particularly contribute to the flavor of spices. In a study of the effluvia of fresh red coffee berries, Mathieu et al. (1996) identified, in two varieties of robusta, a series of mono- and sesquiterpenes, a blend also present in cold pressed oil from pommelos. In fact, the effluvia of red berries attracts the females of the coffee berry borer, a very important pest. Without giving a list of the hydrocarbons identified in this study, let us note that limonene is the most abundant of them, caryophyllene (4,11,11-trimethyl-8-methylenebicyclo[7.2.0]undec-4-ene), followed by humulene (2,6,6,9-tetramethylundeca-1,4,8-triene) and a-pinene (2,6,6-trimethylbicyclo[3.1.1]hept-2-ene), are rather important in two robusta... 

Tingey, D., Turner, D., and Weber, J. (1991) Factors controlling the emissions of monoterpenes and other volatile organic compounds, in Trace Gas Emissions by Plants, edited by T. D. Sharkey, E. A. Holland, and H. A. Mooney. Academic Press, San Diego, CA, pp. 93-120. 

GERSHENZON, J., KREIS, W., Biosynthesis of monoterpenes, sesquiterpenes, diterpenes, sterols, cardiac glycosides and steroid saponins, in Biochemistry of Plant Secondary Metabolism, Annual Plant Reviews, Vol. 2 (Wink, M., ed,), Sheffield Academic Press, Sheffield. 1992, pp. 222-299. 

WISE, M.L., CROTEAU, R. (1999) Monoterpene biosynthesis, in Comprehensive Natural Products Chemistry Isoprenoids, Including Carotenoids and Steroids, Vol 2. (D.E. Cane, ed,), Pergamon Press, Oxford. 1999, pp. 97-154... 

Gershenzon, j. and R. Croteau, Regulation of monoterpene biosynthesis, in Biochemistry of the Mevalonic Acid Pathway to Terpenoids (G. H. N. Towers and H. A. Stafford, eds.). Recent Advances in Phytochemistry Vol. 24, 99-160, Plenum Press, New York, 1990. 

Atta-ur-Rahman and V. U. Ahmad, Monoterpenes and Sesquiterpenes, Vol. 1, C-NMR of Natural Products, Plenum Press, New York, 1992. 

Irving, R. S. and R. P. Adams, Genetic and biosynthetic relationships of monoterpenes, in Terpenoids Structure, Biogenesis and Distribution (V. C. Runeckles and T. J. Mabry, eds.). Recent Advances in Phytochemistry Vol. 6,187-214, Academic Press, New York, 1973. 

Fig. 20.7. Iridoid monoterpenes derived from 8-epi-deoxyloganin (Jensen, 1991 modified and used with permission of the copyright owner, Oxford University Press, Oxford).

Croteau, R. 1986, Biochemistry of monoterpenes and sesquiterpenes of the essential oils , in L. Cracker and J. E. Simon (eds). Herbs, Spices Medicinal Plants, Vol. 1, Oryx Press, Phoenix. 

Abraham, W.-R., H.M.R. Hoffmann, K. Kieslich, G. Reng, and B. Stumpf, 1985. Microbial transformation of some monoterpenes and sesquiterpenoids. In Enzymes in Organic Synthesis, R. Porter and S. Clark, ed., Ciba Foundation Symposium 111, pp. 146-160. London, U.K. Pitman Press. 

Croteau R, Cane DE (1985) Monoterpene and sesquiterpene cyclases. In Law JH, Rilling HC (eds) Methods in enzymology - steroids and isoprenoids. Academic Press, New... 

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