Uw 35500

8/13/2019 Uw 35500

http://slidepdf.com/reader/full/uw-35500 1/4

WEC310

Distillation of Essential Oils 1

Elise V. Pearlstine 2

1. This is document WEC310, one of a series of the Department of Wildlife Ecology and Conservation, University of Florida, Florida Cooperative ExtensionService, Institute of Food and Agricultural Sciences. Published April 2011. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2. Elise V. Pearlstine, research assistant professor, Wildlife Ecology and Conservation Department, University of Florida, Everglades Research and EducationCenter, 3200 E. Palm Beach Rd., Belle Glade, Florida 33430; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information andother services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex,sexual orientation, marital status, national origin, political opinions or affil iations. U.S. Department of Agriculture, Cooperative Extension Service,University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean

A short history of essential oils

Essential oils are volatile, aromatic oils obtainedfrom plants and used for fragrance, flavoring, andhealth and beauty applications.

Historically, aromatic plants provided importantingredients for perfumes, incense, and cosmetics.They have also been used for ritual purposes and incooking and medicine. Egyptians used aromatic plantmaterials to preserve mummies, the Ayurvedicliterature of India includes many references toscented substances, ancient Chinese herbalists valuedthem for their curative properties, and royalty usedrare aromatics to perfume themselves and theirsurroundings. Distillation became an importantmethod of obtaining the healing and fragrantcomponents of various plants and was well-studiedbeginning in the 18th and continuing in the 19thcenturies (Figure 1). In the 1900s, during the time ofthe industrial revolution, component parts of manyessential oils were identified. These componentscould then be synthesized for use in perfume andflavor industries. The art of using essential oilsdeclined during this time but experienced a re-birth inEurope with aromatherapy later in the century. Inrecent years, the use of essential oils has increased in

many industries and in new applications as awarenessof the benefit of naturally derived products grows.

Figure 1. An eighteenth century still from an oldmonograph by Gildemeister.

Plant anatomy and structure as theyrelate to essential oil production

An essential oil is the volatile material derivedfrom plant material by a physical process. The plantmaterial is usually aromatic and of a single botanicalspecies and form; some essential oil plants have adifferent chemical makeup depending on the varietyof plant, and the essential oils are correspondinglyunique. Like grapes used to make wine, "terroir," or

8/13/2019 Uw 35500



the location, soil, climate and weather where the plantis grown, will affect its aromatic properties. The usualmethod of obtaining essential oils from a plant isthrough distillation or expression. Distillation is themost common method and may be water distillation,steam distillation or distillation using a combination

of water and steam. Expression is the pressing of oilfrom a plant part: citrus oils are generally obtainedfrom expression of the peels.

All varieties of plants are used, includinggrasses, annuals, flowers, trees, herbs, shrubs, andmosses. All parts of the plant are used, includingbark, leaves, stems, seeds, fruits, blossoms, evenroots and rhizomes. Essential oils tend to be derivedfrom volatile oils that the plant produces; these areoften terpenes, aldehydes, and oxygenated

compounds such as alcohols. Essential oils are morethan just the familiar lavender; sources list more than300 different essential oils and by-products(roberttisserand.com/essential-oils, Rose 1999 andLawless 1995).

Oil may be in youngest leaves or twigs—newtwigs and leaves of citrus trees contain petitgrain, andpatchouli oil comes from the young twigs and leavesof the patchouli shrub—and production of essentialoil in the plant often coincides with the period ofmost active growth. Flowers may be used as asource—lavender essential oil comes from theflowering tops of the plants (Figure 2). In manyplants, the wood is used and essential oils can begained from distillation of chipped wood. Tall grasseslike lemongrass and palmarosa, or the roots of vetivergrass all contain essential oils often used in perfumery.

Figure 2. Lavender field in Jersey, England.

Some plants yield different oils depending on thepart distilled. For example, orange essential oil comesfrom the peel of the orange fruit and is aninexpensive byproduct of the orange juice industry,while neroli (orange blossom) essential oil is muchmore valuable and comes from distillation of the

flowers of the bitter orange tree. Seeds such as clove,coriander, and black pepper may be shipped to adistillery and stored for distillation at any time of theyear. Many woody essential oils come from maturetrees and may involve destruction of the tree itself.Sandalwood essential oil comes from the roots andheartwood of a small parasitic tree that must be over30 years old before oil can be produced. Mysoresandalwood is grown in India, and these trees are nowendangered. Rosewood comes from a rainforest treeand is obtained from the distillation of wood chips.

Rosewood trees are being over-exploited in theBrazilian rainforest and are a non-sustainable sourceof wood and essential oils.

There are a number of potential reasons for aplant to produce essential oils, including for theiranti-viral, anti-fungal or bactericidal properties.Lemongrass, for example, may have some effect incontrolling a variety of bacteria and molds (Figure 3).Aromatic compounds within a plant may also act toattract or repulse certain insects and animals. Some

attract insects that will visit the plants and collectpollen on their bodies and then deposit that pollen onthe next plant they visit, pollinating it.

History of distillation and essential oilproduction

Distillation of plants has a long and variedhistory that includes distillation of alcoholic spirits aswell as essential oils. While the product may bedifferent, the process is similar. Egypt, Persia, andIndia are some countries where distillation was firstcarried out. It is likely that the first distillations ofaromatic compounds were intended to producedistilled waters or hydrosols, and the essential oilsfloating on top may have been discarded. Turpentine,distilled from pine trees, was one of the first essentialoils to be distilled along with juniper, rosemary, andlavender. These distillations likely occurred duringthe 1500s and were followed by a growth indistillation through the seventeenth and eighteenth

8/13/2019 Uw 35500



Figure 3. Lemongrass plants.

centuries that primarily involved pharmacists. Theseapothecaries perfected methods of distillation andstudied the nature of essential oils. Later, in thenineteenth century, essential oils were widely used asmedicines but gradually became almost moreimportant in perfumes. They also become importantingredients in beverages and foods as flavorings. Inthe United States, turpentine was the most importantand first distilled essential oil, in part due to theenormous areas of pine forests and the need for theproduct. Other early essential oils included sassafras,wormseed, and wintergreen. Peppermint wasproduced in large quantities by the 1800s; large-scaleproduction continues, and much is sold fortoothpaste. With the advent of chemical productionof fragrance and flavor chemicals, essential oilsdecreased in importance. Recent interest inaromatherapy, natural products, and naturalperfumery has led to increased production andinterest in these botanical products.

Basics of essential oil distillation

The essential oils within a plant are generally notsoluble in water, which means they will float on top ofan aqueous (watery) solution. However, they can becarried away from plant material by means of steam

applied in a closed container. The steam can then becondensed using cool water, collected in a containerand the essential oils separated out as they float on topof water produced by the steam. The water thus leftbehind is often aromatic because it containswater-soluble fragrant chemicals from the plant. This

water is called a hydrosol, but may also be referred toas a hydrolat, herbal distillate, or floral water, themost familiar of which are rosewater and orangeflower water.

A basic still consists of three main parts—theboiler, the condenser, and the collector (Figures 4 and5). The boiler provides heat to the water in which theplant material is placed (water distillation), or theboiler may produce steam that is directed through theplant material, which is placed in a container above

the water (steam distillation). In some stills, thesteam is generated elsewhere and pumped throughthe container with the plant material. Some plantmaterials require water distillations; for example, rosepetals will clump when exposed to steam and must beimmersed in water where they can move about freely.Other materials work well when packed into a spaceabove boiling water to allow the steam to passthrough. Many of the best distillations are carried outslowly over low temperatures. Distillation ceaseswhen aromatic compounds are not detected in the

outflow from the still. It is important to maintain astrict control on temperature in order that thebotanical material is not burnt, especially in waterdistillation where the water may run dry.

Figure 4. Illustration of still components.

8/13/2019 Uw 35500



Figure 5. Distillation of palmarosa. Photo by Elise V.Pearlstine.

The steam from either the water or the steamdistillation passes through the plant material. As itpasses through, it ruptures the sacs containing theessential oils. Essential oils are generally quitevolatile and are easily carried into the condenserwhere a cool fluid, often water, is passed over thecollecting tube.

The collecting tube is often coiled and iscontained within an outer container through whichthe cool water flows. This allows the fluid tocondense and drip into the collector. In the collector,the essential oil is separated from the hydrosol oraqueous portion. Distillation may take only a fewhours or more than 20, depending on the plant beingdistilled and the method. Both products, the oil and

the hydrosol, can then be bottled separately and usedin a variety of ways, including aromatherapy, beautyproducts, room scents, or natural perfumes. If ahydrosol is the final product, the essential oil isgenerally not removed and is included as part of theproduct.

References and Further Reading

Arctander, Steffen. 1960. Perfume and Flavor Materials of Natural Origin. Published 1994 byAllured Publishing Corporation, Carol Stream, IL.

Firth, Grace. 1983. Secrets of the Still. EPMPublications, Inc. McLean, VA.

Guenther, Ernest. 1948. The Essential OilsVolume One: History-Origin inPlants-Production-Analysis. D. Van NostrandCompany, Inc. New York, NY.

Gildemeister, E. and Fr. Hoffman 1900. TheVolatile Oils. Published by Pharmaceutical ReviewPubl. Co., Milwaukee, WI.

Lawless, Julia. 1995. The Illustrated Encyclopedia of Essential Oils: The Complete Guideto the Use of Oils in Aromatherapy and Herbalism.Harper Collins Publishers, London.

Rose, Jeanne. 1999. 375 Essential Oils and Hydrosols. Frog Ltd., Berkeley, CA.

Documents

Uw 35500