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An essential oil is any concentrated, Hydrophobic Liquid containing volatile Aroma Compound s from Plant s. They are also known as '''volatile''' or '''ethereal''' oils, or simply as the "oil of" the plant material from which they were extracted, such as ''oil of clove''. The term '''essential''' indicates that the oil carries distinctive scent (essence) of the plant, not that it is an especially important or fundamental substance. Essential oils do not as a group need to have any specific chemical properties in common, beyond conveying characteristic fragrances. They are not to be confused with Essential Fatty Acid s. Essential oils are generally extracted by . Various essential oils have been used medicinally at different periods in history. Medical Applications proposed by those who sell medicinal oils vary from skin treatments to remedies for cancer, and are often based on historical use of these oils for these purposes. Such claims are now subject to regulation in most countries, and have grown correspondingly more vague, to stay within these regulations. Interest in essential oils has revived in recent decades, with the popularity of Aromatherapy , a branch of Alternative Medicine which claims that the specific aromas carried by essential oils have curative effects. Oils are volatilized or diluted in a carrier oil and used in massage, or burned as incense, for example. PRODUCTION See Also: Extraction (fragrance) Distillation See Also: distillation Today, most common essential oils, such as lavender, peppermint, and eucalyptus, are distilled. Raw plant material, consisting of the Flower s, Leaves , Wood , Bark , Root s, Seed s, or Peel , is put into an Alembic (distillation apparatus) over Water . As the water is heated the steam passes through the plant material, vaporizing the volatile compounds. The vapors flow through a coil where they condense back to liquid, which is then collected in the receiving vessel. Most oils are distilled in a single process. One exception is Ylang-ylang ( Cananga Odorata ), which takes 22 hours to complete through a Fractional Distillation . The water recondensed from the distillation process is referred to as a hydrosol, hydrolat, Herbal Distillate or plant water essence, which may be sold as another fragrant product. Popular hydrosols are Rose Water , Lavender Water , Lemon Balm , Clary Sage and Orange Blossom Water . The use of herbal distillates in Cosmetics is increasing. Some plant hydrosols have unpleasant smells and are therefore not sold. Expression Most citrus peel oils are usually expressed mechanically, or '' Cold-pressed ''. Due to the large quantities of oil in citrus peel and the relatively low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils that are obtained as By-product s of the commercial citrus industry are even cheaper. Prior to the discovery of Distillation , essential oils (EO) were extracted by pressing. Solvent extraction Most flowers contain very little volatile oil to undergo expression and their chemical components are too delicate and easily denatured by the high heat used in steam distillation. Instead, a Solvent such as Hexane or Supercritical Carbon Dioxide is used to extract the oils. Extracts from hexane and other hydrophobic solvent are called '' Concrete s'', which is mixture of essential oil, waxes, resins, and other Lipophilic (oil soluble) plant material. Although highly fragrant, concretes contain large quantities of non-fragrant waxes and resins. As such another solvent, often Ethyl Alcohol , which only dissolves the fragrant low-molecular weight compounds, is used to extract the fragrant oil from the concrete. The alcohol is removed by a second distillation, leaving behind the '' Absolute ''. Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. This method has many benefits, including avoiding Petrochemical residues in the product. It does not yield an absolute directly. The supercritical carbon dioxide will extract both the waxes and the essential oils that make up the concrete. Subsequent processing with liquid carbon dioxide, achieved in the same extractor by merely lowering the extraction temperature, will separate the waxes from the essential oils. This lower temperature process prevents the decomposition and denaturing of compounds and provides for a superior product. When the extraction is complete, the pressure is reduced to ambient and the carbon dioxide reverts back to a gas, leaving no residue. Although supercritical carbon dioxide is also used for making Decaffeinated Coffee , the actual process is different. Production quantities ESSENTIAL OIL USE IN AROMATHERAPY See Also: Aromatherapy DILUTION Essential oils are usually with water. Instead, they can be diluted in Solvent s like pure 100% Ethanol (''alcohol''), Polyethylene Glycol , or Oil s. RAW MATERIALS See Also: List of essential oils Essential oils are derived from various sections of plants. Some, like Orange oil, are derived from any of several sections of the plant. Rose oil See Also: Rose oil The most well-known essential oil is probably Rose Oil , produced from the petals of '' Rosa Damascena '' and '' Rosa Centifolia ''. Steam-distilled rose oil is known as "rose otto" while the solvent extracted product is known as "rose absolute". DANGERS Because of their concentrated nature, EOs generally should not be applied directly to the skin in their undiluted or "neat" form. Some can cause severe irritation or provoke an allergic reaction. Instead, essential oils should be blended with a vegetable carrier oil (also referred to as a base or "fixed" oil) before being applied. Common carrier oils include olive, almond, hazelnut and grapeseed. Common ratio of essential oil disbursed in a carrier oil is 0.5–3% (most less than 10%) and depends on its purpose. Some EO's including many of the Citrus peel oils, are photosensitizers, increasing the skin's reaction to sunlight and making it more likely to burn. Industrial users of essential oils should consult the Material Safety Data Sheet s (MSDS) to determine the hazards and handling requirements of particular oils. ; Gynaecomastia |
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