Extraction of Essential Oils

Manzan, A.C. et al.. Extraction of essential oil and pigments from Curcuma longa [L] by steam distillation and extraction with volatile solvents, J. Agric. Food Chem., 51, 6802, 2003. 

Steam distillation is used extensively in the extraction of essential oils from plant... 

Solvent extraction of essential oils tends to generate material that is contaminated with solvent (and cannot be sold) and mechanical pressing of a plant usually generates too poor a yield to be economically viable. 

Gogus, E, Ozel, M.Z., Lewis, A.C. (2005) Superheated water extraction of essential oils of Origanum micranthum. J. Chromatogr. Sci. 43 87-91. 

D.A. Moyler, CO2 extraction of essential oils Part III. pimento berry, coriander and celery seed oil, In Flavors and off-flavors, Developments in food science 24 (ed. G. Charalambous), Elsevier, Amsterdam, (1990) 263. 

Lucchesi, M.E., F. Chemat, and J. Smadja. 2004. Solvent-free microwave extraction of essentials oil from aromatic herbs Comparison with conventional hydro-distillation. J. Chromatogr. A 1043 323-327. 

Steam distillation is the most common process for the extraction of essential oils from plants (1-3). It provides a fast and simple way to obtain aromatic components which bear the characteristic odor of that species. However, "still notes" or "burnt notes" are frequently found in freshly distilled oil. The off-flavor results in most cases from thermally induced hydrolytic or degradative reactions (4). 

Uses The alicyclic hydrocarbons have numerous industrial applications. Cyclopropane (C3H6) is used as an anesthetic. Cyclohexane (CgH ) is used as a chemical intermediate as an organic solvent for oils, fats, waxes, and resins and for the extraction of essential oils in perfume manufacturing industries. Cyclohexene (C6H10) is used in the manufacture of maleic acid, cyclohexane carboxylic acid, and adipic acid. Methyl cyclohexane (C7H14) is used for the production of organic synthetics such as cellulose ethers. These compounds are used in different industries such as adipic acid makers, benzene makers, fat processors, fungicide makers, lacquerers, nylon makers, oil processors, paint removers, plastic molders, resin makers, rubber makers, varnish removers, and wax makers. 

Ferreira, S.R.S., Meireles, M.A.A. and Cabral, F.A. (1 993) Extraction of essential oil of black pepperwith liquid carbon dioxide. Journal of Food Engineering 20, 121-133. 

Lucchesi, M.E., Smadja, J., Bradshaw, S., Louw, W. and Chemat, F. (2007) Solvent free microwave extraction of Elletaria cardamomum L. a multivariate study of new technique for the extraction of essential oil. journal of Food Engineering 79, 1 079-1 086. 

Tuan, D.Q. and Hangantileke, S.G. (1997) Liquid C02 extraction of essential oil from star anise fruits (lllicium verum H.). Journal of Food Engineering 31,47-57. 

Bernard, T., Perineau, F., Delmas, M. and Caset, A. (1989) Extraction of essential oils by refining of plant materials. II. Processing of products in the dry state lllicium verum Hooker (fruit) and Cinnamomum zeylanicum (bark). Flavour and Fragrance Journal 4, 85-90. 

Moyler, D.A., Bowing, R.M. and Stevens, M.A. (1994) C02 extraction of essential oils. PartV. Nutmeg and mace oils. In Charalambous, C. (ed.) Spices, Herbs and Edible Fungi. Elsevier Science, B.V., Amsterdam, pp. 145-170. 

Spricigo, C.B., Pinto, L.T., Bolzan, A. and Novais, A.F. (1 999) Extraction of essential oil and lipids from nutmeg by liquid carbon dioxide. Journal of Supercritical Fluids 15, 253-259. 

Solvent-free microwave extraction (SFME) is a recently developed green technique, performed in atmospheric conditions without adding any solvent or water and being applied to the extraction of essential oil from fresh plant or dried materials. The essential oil is evaporated by the in situ water in the plant materials. Wang et al. 

Rodrigues, V.M., Rosa, P.T.V., Marques, M.O.M., Petenate, A.J. and Meireles, M.A.A. (2003) Supercritical extraction of essential oil from aniseed (Pimpinella anisum F) using COq solubility, kinetics, and composition data, journal of Agricultural and Food Chemistry 51(6), 1518-1523. 

There are various methods of extraction of essential oils, such as steam distillation,... 

Distillation is the most commonly used method for the extraction of essential oils. There are two techniques of distillation water and steam. 

Maceration is the removal of substances by soaking materials in an appropriate liquid. Hot fat is used in maceration to extract essential oils from plant material. The saturated fat is then washed with alcohol to leave pure essential oil, e.g. calendula oil. Maceration is used for extraction of essential oils that cannot be extracted by distillation. 

The extraction of essential oil from oxegano-Origanum virens L.- using liquid carbon dioxide (7 MPa and 298 K) and supercritical carbon dioxide (10 and 15 MPa and 313 K) was investigated. Experimental results were obtained in a laboratory scale plant equipped with a 100 mL tubular extractor. 

Extraction of essential oils from plants using supercritical fluids is a very interesting application of this technology since it offers the possibility to improve the extraction yields and/or to obtain new flavours or aromas by the control of pressure and temperature of extraction. 

Based on the foregoing, efficiency in the extraction of essential oils from plants appears to depend strongly on the particular type of oil and also, possibly, on the sample matrix, so whether SFE surpasses SD-SE in this respect, or vice versa, cannot be stated unambiguously. The SFE technique does surpass ultrasonic extraction (USE) for the removal of organic, low-polar compounds [175-177]. On the other hand, it compares unfavourably with MAE in this respect [177-179]. Thus, Lopez-Avila et al. used MAE, SFE, SOX and USE to extract 94 compounds on the list of EPA method 8250 and found the first technique to provide recoveries above 80% for 51 such compounds, over the range... 

Extraction of essential oils is one of the most time- and effort-consuming processes in the analysis of the constituents of plants. Various extraction methods were traditionally employed, depending on the material or the available devices. The most commonly used methods are steam distillation and distillation-solvent extraction. The introduction of innovative extraction methods, such as microwave-assisted extraction (MAE) and supercritical fluid extraction (SEE), has led to significant improvement, not only in the analytical performance, but also in the accuracy and reproducibility of methods. 

Supercritical fluid extraction and microwave-assisted extraction have been recently applied to the extraction of essential oils. Both techniques are based on the application of high pressures and temperatures for the total extraction of analytes. Supercritical fluid extraction has... 

The use of SFE and MAE has been generalized to many essential oils and different samples. These techniques have improved recoveries in the determination of most organic additives, as well as permitted considerable reductions in solvent volume and extraction time. However, the comparison of extraction methods was usually reduced to relative recoveries of target analytes, ignoring important analytical parameters of the method. Selectivity is one of these, as the coextraction of other organics from the matrix usually requires a postextraction cleanup step before chromatographic analysis. There is still much effort to be carried out in this field in order to optimize the extraction of essential oils from different natural matrices. The selection of the best extraction method depends on the components to be extracted, and this is something to be carefully considered in each particular case. 

Cyclohexane is used as a solvent for lacquers, resins, fats, oils, and waxes, in paint and varnish remover, in the manufacture of nylon, in the extraction of essential oils, and in analytical chemistry for molecular... 

The major applications of dense gases, fluids above or in the vicinity of the critical point, have been for the extraction of specific compounds from solid matrices or liquid mixtures. Well-known examples include the decaffeination of coffee, extraction of olfactory compounds for the perfume and food industries, the extraction of essential oils, and the use of SCFs for the extraction of heavy fractions from distillates. These processes benefit from the selectivity of dense gases. A variety of new applications has been identified for which the properties of dense gases, other than the solvent power, are utilized. One field is the utilization of dense gases as a reactant for reactions. The dense gas processes for the production of low density polyethylene (LDPE) by free radical polymerization, and more recently, the manufacture of fiuoropolymers have annual outputs measured in bulk tonnages. 

SCF processing on a large scale had its earliest success with extraction processes. The dccaffci nation of coffee and tea is carried out in tonnage quantities, and methylene chloride residues thus arc eliminated. Extraction of essential oils and flavors has been commercially successful. Because SCF often have only limited solvation properties for some desired materials, SCF processes abound in which nonsupercritical solvents are added at critical points. 

Supercritical fluid extraction has been applied to plants and food samples with different objectives. Regarding plants, it has been applied for the extraction of active compounds used in the elaboration of pharmaceutical preparations or for the extraction of essential oils, widely used in the pharmaceutical industry as well. In the former case, SFE has been used as a suitable tool for the monitoring of dosage levels of drugs administrated to animals through their feeds and also for the extraction of active compounds from food, thus allowing characterization of some properties of the food such as the vitamin content. 

Extraction of Essential Oils from Plants. Essential oils are aromatic substances widely used in the perfume industry, the pharmaceutical sector, and the food and human nutrition field. They are mixtures of more than 200 compounds that can be grouped basically into two fractions a volatile fraction, which constitutes 90-95% of the whole oil, and a nonvolatile residue, which constitutes the remaining 5-10%. The isolation, concentration, and purification of essential oils have been important processes for many years, as a consequence of the widespread use of these compounds. The common methods used are mainly based on solvent extraction and steam distillation. SFE has been used for the extraction of essential oils from plants, in an attempt to avoid the drawbacks linked to conventional techniques (57). Such is the case with the extraction of flavor and fragrance compounds, such as those from rose (58), rosemary (59), peppermint (60), eucalyptus (61), and guajava (62). The on-line coupling of the extraction and separation ietermi-nation steps (by SFE-GC-FID) has been proposed successfully for the analysis of herbs (63) and for vetiver essential oil (64). 

The first apphcations of MAP that were disclosed pubhcly dealt with the extraction of essential oils from plant products [8], although the patented technology apphes to the extraction of a variety of chemical substances from a wide range of matrices such as water, soils, animal and plant tissues, as well as a variety of man-made products [1-6]. The fields of apphcation are also very diversified and include environmental, agricultural, food, biomedical, pharmaceutical, consumer products, and process monitoring and control. 

Verschuere et al. [25] observed a similar trend in the extraction of essential oils and bitter acids of hops when using samples as small as 0.25 grams. They observed, "Compared to conventional methods for extraction of alpha-acids and beta-acids, % rsd s are higher with SFE. Typical values are in the order of 10 % for 6 replicates on the same hop sample. This is due to the small sample size requirements if contamination problems have to be avoided. With the extractor used and taken into consideration that the concentration of the bitter acids in hops range as high as 10 %, 250 milligram sample size is the maximum which can be extracted without breakthrough or contamination (of the lipid-free... 

SC-C02 extraction of essential oils from fruit and various other parts of citrus trees was investigated in an EU sponsored project (AGRE-00S8). Experimental parameters were identified for optimal extraction leading to design of suitable equipment (49). SC-C02 extraction of P-cryptoxanthin from citrus press cake was investigated by Sangbin-Lim et al. (SO). 

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