Essential oil

Essential oil is a natural substance found in various plant parts, including flowers, leaves, roots, bark, seeds, fruits, stems, and gums. Essential oils provide the essence—or the specific odor or flavor—of the plant. They may be extracted from plant material using several techniques.

Among the most commonly used essential oils are lavender, peppermint, tea tree, orange, lemon, eucalyptus, rosemary, oregano, chamomile, clove, frankincense, and myrrh. Essential oils may be used alone, mixed into plain oil, known as carrier oil, which helps diffuse and spread the essential oil; or blended with other materials to become part of a diverse range of products, including perfumes, cosmetics, soaps and cleaning products, candles, food, beverages, over-the-counter and prescription medicines, and insecticides. Their fragrant nature makes essential oils an important part of aromatherapy, which seeks to alter mood and improve health through the use of fragrances.

History

People have used fragrant plants as part of healing and religious practices for centuries. Ancient Egyptians used essential oils during the mummification process and for anointing people and images of gods and goddesses during religious rituals. During the third century BCE, the people of China and India relied on essential oils for their curative powers. Ancient Greeks and Romans commonly used essential oils to treat infections.

During the Middle Ages, knights returning home from the Crusades brought essential oils and the knowledge of how to make and use them to Europe. Treatments using essential oils developed by the people of India in the third century BCE were found to be more effective than European medicines against the bubonic plague in the fifteenth century. Across the Atlantic, both Native Americans and European settlers who immigrated to America relied heavily on aromatic plants and their essences for their healing properties.

In 1910, a laboratory explosion burned the hands of French chemist René-Maurice Gattefossé (1881–1950). When gangrene set in, Gattefossé tried lavender oil as a treatment and was amazed at how quickly healing began. He also discovered the healing effects of lavender’s scent and is credited with starting the practice of aromatherapy.

Methods of Extraction

The method used to extract an essential oil depends on the part of the plant it comes from and the plant’s fragility. The two most commonly used techniques are distillation and expression. These two techniques appear to date back to the earliest known uses of essential oils.

Distillation uses either steam alone or water and steam to separate the desired components from the rest of the plant matter. In this process, plant matter is placed inside a still, beneath which is a source of steam. The still is sealed, and the steam (or steam and water) is applied to break down the plant matter. The scented components rise within the still as vapor and collect in a condenser, which allows the vapor to cool and return to liquid form. Water and oil do not naturally mix, so the oil can easily be collected from the liquid. Many essential oils are extracted through distillation.

Expression, also known as cold pressing, involves puncturing and squeezing plant matter to release essential oils. For centuries, expression was done manually. In modern times, however, machines are used for pressing, and centrifuges separate the desired oil from the rest of the liquids. Citrus oils often are collected through expression.

In some cases, neither distillation nor expression will effectively separate the essential oil from the plant matter. When plant matter is too delicate for expression and too heat sensitive for distillation, solvents may be used to extract essential oil. Jasmine oil, for example, often is extracted through the use of solvents such as hexane and petroleum ether. Another method, enfleurage, is used when the plant material contains such a small amount of oil that other methods of gathering it are not cost effective. Enfleurage involves spreading unscented oil on a glass plate and layering it with the plant material. Additional plant matter—most often flower petals—is added until the unscented oil has absorbed all the essential oil possible, at which point it is collected.

Twenty-First Century Uses

During the nineteenth and twentieth centuries, many people turned to synthesized chemicals to clean, deodorize, flavor, and otherwise replace essential oils in everyday life. In the twenty-first century, however, a trend toward using more natural and environmentally friendly materials has developed, and interest in essential oils has grown. While government oversight agencies apply a cautious approach to claims about the healing properties and medical benefits of essential oils, laboratory studies continue to reveal potential new uses for them. In some early twenty-first century studies, lavender and tea tree oil have been shown to be effective against infections caused by fungus and bacteria, and clove oil has been recognized as a topical anesthetic particularly useful for temporary relief of dental pain.

Interest in essential oils as replacements for some of the antibiotics used to combat infections in livestock, especially those destined for human consumption, has also grown. Several studies have shown that chickens fed a feed mixture laced with oregano oil are less likely to contract certain common poultry infections.

The increasing threat of the development of infections resistant to known antibiotics also has driven scientists to investigate the possibility of using essential oils to both prevent and treat certain infections in humans. For instance, both tea tree oil and lemongrass oil have been shown to provide effective germ-killing properties when used in hand sanitizers, while vapors from tea tree oil helped speed the healing of wounds infected with staph.

Bibliography

Dayton, Lily. "Sure, Essential Oils Smell Great. But Are They Good for Anything Else?" Los Angeles Times. Los Angeles Times Media Group, 16 Jan. 2016. Web. 16 Jan. 2016. http://www.latimes.com/health/la-he-essential-oils-20160116-story.html. Accessed 22 Nov. 2024.

Essential Oils for Beginners: The Guide to Get Started with Essential Oils and Aromatherapy. Berkeley, CA: Althea Press, 2013. Print.

"Essential Oils: More Harmful Than Helpful?" American Lung Association, 8 Jan. 2024, www.lung.org/blog/essential-oils-harmful-or-helpful. Accessed 22 Nov. 2024.

"Extraction Methods of Natural Essential Oils." TNAU Agritech Portal. Tamil Nadu Agricultural University, University of Coimbatore, India. Web. 16 Jan. 2016. http://agritech.tnau.ac.in/horticulture/extraction‗methods‗natural‗essential‗oil.pdf. Accessed 22 Nov. 2024.

Rodriguez, Tori. "Essential Oils Might Be the New Antibiotics." The Atlantic. The Atlantic Monthly Group, 16 Jan. 2015. Web. 16 Jan. 2016. http://www.theatlantic.com/health/archive/2015/01/the-new-antibiotics-might-be-essential-oils/384247/. Accessed 22 Nov. 2024.