Essential oils, economic plants

The essential oils and plant materials containing such oils are natural products of great economic importance. The main use is in the perfumery and cosmetic industry and in food processing as spices. A few essential oils or pure substances isolated from such oils are used in pharmacy for several purposes ... 

This is another simple, economical and harmless process for increasing the yield of essential oils from plant materials. Cashew shell oils are extracted via this method on an industrial scale. In this process the cashew shells are heated with cashew shell oil and, after a certain period of time, some of the oil is removed and the process is repeated with fresh cashew shells. 

SEME is a recent method of extraction, patented in 2004, with the specific objective of obtaining essential oil from plant material [45, 46]. Based on a relatively simple principle, SFME involves placing the vegetable material in a microwave reactor without addition of solvent or water. SFME is a combination of microwave heating and distillation, and is performed at atmospheric pressure. In terms of quality and quantity, SFME seems to be more competitive and economic than classical methods such as hydro or steam distillation [59, 60]. 

Furthermore, the modernization of agricultural techniques and the growth of plantation areas result in better economical factors for the production of essential oil-bearing plants, creating workplaces in developing countries of Southeast Asia, Africa, and South America as well as further development of modern farms in the United States and Europe (Mediterranean area, Balkans). Despite some regulatory restrictions (EU, REACH, FDA, etc.), essential oils are and will have an... 

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is widely used in foods, beverages, perfumes and the pharmaceuticals industries. Biotransformation of isoeugenol from essential oil to vanillin represents an economic route for the supply of vanillin, which has a limited supply due to the availability of vanilli pod plants. The conversion yield of isoeugenol to vanillin by the whole-cell biotransformation process of Bacillus fusiformis was low due to the product inhibition effect. Adding resin HD-8 to the whole-cell biotransformation eliminated the product inhibition effect, yielding 8 gL 1 of vanillin in the final reaction mixture [27]. The resin HD-8 also facilitated the separation of vanillin from the used substrate. The recovered isoeugenol can be used for the subsequent biotransformation reaction. 

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. 

Lavandin is produced by a hybrid plant Lavandula intermedia or Lavandula hybrida, which was bred by crossing the true lavender (Lavandula angustifolia) with spike lavender (Lavandula latifolia). Lavandin is sometimes called bastard lavender. Hybrids are widespread in horticulture, where they are bred to produce plants with the desired properties of the parents. The lavandin plants are easier to grow at lower altitudes (400-600 metres), yielding almost twice as much oil as the true lavender plant. Again, this is economically favourable and lavandin essential oil is particularly useful for the cosmetic and fragrance industries. 

Supercritical fluid extraction has now found a lot of applications in different fields (polymers, aromas and essential oils, fats, natural products, soil decontamination...) and several production units are operated in agroalimentary (coffee, hop...) and pharmaceutical industries. In order to estimate the economical interest of these applications, technical and economical extrapolation methods have been developed. These methods are dependent of the nature of the extraction and are based on experimental results obtained on pilot plant units. We describe here a general extrapolation procedure, and a case study is presented to illustrate an economical estimation of a supercritical fluid extraction. 

Energy availability. Power and steam requirements are high in most industrial plants, and fuel is ordinarily required to supply these utilities. Consequently, power and fuel can be combined as one major factor in the choice of a plant site. Electrolytic processes require a cheap source of electricity, and plants using electrolytic processes are often located near large hydroelectric installations. If the plant requires large quantities of coal or oil, location near a source of fuel supply may be essential for economic operation. The local cost of power can help determine whether power should be purchased or self-generated. 

The MEP pathway is the starting material of major plant terpenoids of economic value e.g., monoterpenes from essential oils, diterpenoids with potent biologic activity (taxol, ginkgolides), vitamins (tocopherol), or vitamin precursors (carotenoids). The first attempts to overexpress some of its genes (especially dxs or dxr) led to enhanced carotenoid production in tomato (18) or monoterpenes in mint (19). 

The fact that menthol is produced from both renewable and fossil feedstocks allows for an interesting study in sustainability. In order to produce the same crop year after year, it is necessary to use fertilisers to replenish the nitrogen and minerals which the plant takes from the soil. Secondary metabolites such as menthol and essential oils occur at a level of, at most, only a few per cent of the dry weight of the herb. Therefore, in order to produce an economic return, it is necessary to use efficient, mechanical methods of cultivation and harvesting. A full life cycle analysis of menthol production reveals that production from cultivation of mint plants consumes more fossil fuel, produces more carbon dioxide effluent and has more environmental impact than either of the leading synthetic routes. 

From the economic and pharmaceutical point of view the main components of S. sclarea are the essential oil and a diterpene alcohol named sclareol. The former was first produced by Schimmel [17] and is usually obtained by steam distillation of fresh plant material. The latter is usually obtained by counter current extraction of spent steamed plant material using hexane as the solvent. After concentration by solvent evaporation a partial concrete is obtained and sclareol is selectively removed by a second counter current extraction with a polar solvent. In the USA, most of the S. sclarea is grown for the production of this non -volatile compo-... 

Because they are biochemically similar to zygotic embryos (3,4), somatic embryos also present an opportunity for vitro production of numerous secondary plant products which are associated with seeds. For example, essential oil, flavor, and aroma components found in seeds of celery (5), cocoa (6,7), and oil palm (8) are produced by somatic embryos. The ability to control and develop this process may permit more economical and reliable production of certain plant products on an industrial level. 

Once the oils are obtained, the fundamental contribution of the organic chemistry to the industry resides in their characterisation, as their chemical composition may vary even whithin one botanical species. These variations might be due to the presence of different chemotypes, according to the plant adaptation to the surroimding environment, as well as its state of development. We have to take into account the fact that it is the composition of the essential oils what provides their intrinsic properties and economic value. 

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