The sense of smell is the most powerful of senses. It is capable of bringing up long-forgotten memories, feelings of delight and sorrow, as well as stimulating sexual responses. Our noses are said to be able to identify over 10,000 scents.
Aromatherapy developed because of the far-reaching effects of our sense of smell. Aromatherapy is simply the science of using oils distilled from plants, including trees, flowers, and herbs, to heal the spirit, mind, and body. A plant’s life force is stored in the oil. When penetrated into the skin or inhaled, these oils have the power to alter moods, heal cells, stimulate circulation, and enter the bloodstream to heal the body.
Aromatherapy has been used for eons to heal and enhance our sense of well-being. It has been used in skin care since the Egyptian culture, some 5,000 years ago. For thousands of years, man has used the sense of smell ritualistically through incense, perfumes, lotions, and in healing.
Distilling essential oils
Essential oils are the essence of the plant. Plants usually contain 1 to 10% essential oil. The oils are usually extracted by a distillation process.
Extracting essential oils
Extraction is sometimes done with alcohol. Sometimes it is done mechanically, like for citrus fruits. For example, the citrus peel is squeezed and the essential oil oozes out.
Robert B. Tisserand, author of The Art of Aromatherapy, suggests that the essence of a plant “is like its personality. All animals, including humans, have their own characteristic smell.” [Robert B. Tisserand, The Art of Aromatherapy, The Healing and Beautifying Properties of the Essential Oils of Flowers and Herbs, Rochester, VT: Destiny Books, 1977, p. 15.]
There is little doubt of the importance scents play in our lives. Scents affect our sexuality and arousal, relaxation, memory, moods, emotions, and help the body by promoting healing. It is estimated there may be up to 500,000 different scents on this planet.
The function of essential oils
One theory is that the function of essential oils is to regulate the rate of transpiration in plants. Moisture from essential oils has different heat conductivity than of just moisture alone, so the essential oil and its scent is a protection to retain moisture and to maintain temperature.
Many things can affect the essential oil within the plant. In some plants, the essential oil can be found in different parts of the plant during different times of the day or year. During the fecundation process, flowering, the essential oil can change drastically; also many external conditions such as fertilization, light, heat, moisture, altitude, even parasites can change the anatomical structure of the plant, hence the essential oil.
Most essential oils are formed at an early part of the plant’s life, and it is best to extract it before the fecundation process.
The Condensed Chemical Dictionary defines essential oils as “volatile oils derived from plants, and usually carrying essential odor or flavor of the plant used. Chemically, essential oils are often principally terpenes (hydrocarbons), but many other classes of compounds are also found. They are to be distinguished from fixed oils such as linseed oil or coconut oil in that the latter are glycerides of fatty acids and hence saponifiable, meaning capable of being converted into soap by reaction with an alkali. Essential oils (except for those containing esters) are unsaponifiable. Some essential oils are nearly pure single compounds, as oil of wintergreen, which is methyl salicylate. Others are mixtures as spirits of turpentine (pinene, dipentene), and oil of bitter almond (benzaldehyde, hydrocyanic acid). Some contain resins in solutions and are then called oleoresins or balsams. [The Condensed Chemical Dictionary, Fifth Edition. Revised and enlarged by Arthur and Elizabeth Rose, New York: Reinhold Publishing Corp., 1956, p. 440.]
Essential oils are derived from the flowers and plants to which they supply the characteristic odors commonly identified with those plants.
Methods of extraction
- by steam distillation
- by pressing (fruit rinds)
- by solvent extraction
- by enfleurage (employed for those very delicate oils whose odors are destroyed by even moderate heat; i.e., exposing odorless fats to the exhalations of flowers until they become strongly charged with the perfume)
The Chemistry of Essential Oils and Artificial Perfumes defines essential oils as “odoriferous bodies of an oily nature obtained almost exclusively from vegetable sources, generally liquid (sometimes semisolid or solid) at ordinary temperatures, and volatile without decomposition.” It also states that “an absolute scientific definition of the term essential or volatile oils is hardly possible.” [Ernest J. Parry, The Chemistry of Essential Oils and Artificial Perfumes, Vol. II, 4th rev. ed., London, England: Scott, Greenwood and Son, 1922, p. 1.]
Sometimes the essential oils come from the entire plant, sometimes from the tree gum, or the bark, leaves, or root, or as in the orange family, the peel of the fruit. Many theories state that the majority of essential oils are by-products of the “metabolic processes of cell life, such as are many of the alkaloids, colouring matters, and tannins.” [Ibid.] The essential oil can be part of the excretionary functions, pathological or fibrovascular functions, or the fundamental tissue.
Odors and chemical constitution: Substances of high molecular weight are usually odorless. In order for a substance to be odorous it also must be somewhat soluble in both water and the lipoid fats of the nose cells.