An essential oil is “essential” in the sense that it contains the “essence of” the plant’s fragrance—the characteristic fragrance of the plant from which it is derived. The term “essential” used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a given living organism.
Essential oils are generally extracted by distillation, often by using steam. Other processes include expression, solvent extraction, sfumatura, absolute oil extraction, resin tapping, wax embedding, and cold pressing. They are used in perfumes, cosmetics, soaps and other products, for flavoring food and drink, and for adding scents to incense and household cleaning products.
Essential oils are often used for aromatherapy, a form of alternative medicine in which healing effects are ascribed to aromatic compounds. Aromatherapy may be useful to induce relaxation, but there is not sufficient evidence that essential oils can effectively treat any condition. Improper use of essential oils may cause harm including allergic reactions and skin irritation, and children may be particularly susceptible to the toxic effects of improper use.
Used in perfumery and aromatherapy, absolutes are similar to essential oils. They are concentrated, highly aromatic, oily mixtures extracted from plants. Whereas essential oils are produced by distillation, boiling or pressing, absolutes are produced through solvent extraction, or more traditionally, through enfleurage.
Production – First, plant material is extracted with a hydrocarbon solvent, such as hexane, to yield a concrete. The concrete is then extracted with ethanol. The ethanol extract is cooled (e.g., to −15 °C) to solidify waxes, and cold filtered to yield a liquid extract. When the ethanol evaporates, an oil—the absolute—is left behind.
Traditionally, the absolute was obtained by enfleurage, where the resulting pommade was extracted with ethanol to yield the absolute.
Character and use – Some raw materials are either too delicate or too inert to be steam-distilled and can only yield their aroma through solvent extraction. Examples of these are jasmine and beeswax. Absolutes in demand include rose, jasmine, tuberose, jonquil, ylang-ylang, mimosa, boronia, lavender, lavandin, geranium, clary sage, violet, oak moss, tonka bean.
Rose oil, jasmine absolute, tuberose absolute, orris root oil, ambrette seeds oil, angelica root oil, and orange flower oil are valuable and expensive fragrance and flavor ingredients.
Residual solvents may remain in the absolutes. Therefore, some absolutes are considered undesirable for aromatherapy.
Plant fragrance "essense"
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