Essential oil

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For the Midnight Oil album, see Essential Oils (album).Not to be confused with essential fatty acid or fragrance oils.

An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. 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. [1] 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 living organism. [2]

Contents

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, air fresheners 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 it can effectively treat any condition. [3] Improper use of essential oils may cause harm including allergic reactions, inflammation and skin irritation. Children may be particularly susceptible to the toxic effects of improper use. [4] [5] Essential oils can be poisonous if ingested or absorbed through the skin. [5]

Production

Distillation

Most common essential oils such as lavender, peppermint, tea tree oil, patchouli, and eucalyptus are distilled. Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, 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 is purified through a fractional distillation.

The recondensed water is referred to as a hydrosol, hydrolat, herbal distillate, or plant water essence, which may be sold as another fragrant product. Hydrosols include rose water, lavender water, lemon balm, clary sage, and orange blossom water.

Expression

Most citrus peel oils are expressed mechanically or cold-pressed (similar to olive oil extraction). [6] Due to the relatively large quantities of oil in citrus peel and low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils are obtained as byproducts of the citrus industry.

Before the discovery of distillation, all essential oils were extracted by pressing. [7]

Solvent extraction

Most flowers contain too little volatile oil to undergo expression, but 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. [8] Extracts from hexane and other hydrophobic solvents are called concretes , which are a 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. Often, another solvent, such as ethyl alcohol, is used to extract the fragrant oil from the concrete. The alcohol solution is chilled to −18 °C (0 °F) for more than 48 hours which causes the waxes and lipids to precipitate out. The precipitates are then filtered out and the ethanol is removed from the remaining solution by evaporation, vacuum purge, or both, leaving behind the absolute .

Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. This method can avoid petrochemical residues in the product and the loss of some "top notes" when steam distillation is used. 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. When the extraction is complete, the pressure is reduced to ambient and the carbon dioxide reverts to a gas, leaving no residue.

Production quantities

Estimates of total production of essential oils are difficult to obtain. One estimate, compiled from data in 1989, 1990, and 1994 from various sources, gives the following total production, in tonnes, of essential oils for which more than 1,000 tonnes were produced. [9]

OilTonnes
Sweet orange 12,000
Mentha arvensis 4,800
Peppermint 3,200
Cedarwood 2,600
Lemon 2,300
Eucalyptus globulus 2,070
Litsea cubeba 2,000
Clove (leaf)2,000
Spearmint 1,300

Uses and cautions

Taken by mouth, many essential oils can be dangerous in high concentrations. Typical effects begin with a burning feeling, followed by salivation. [10] Different essential oils may have drastically different pharmacology. Some act as local anesthetic counterirritants and, thereby, exert an antitussive (cough suppressing) effect. [10] [11] Many essential oils, particularly tea tree oil, may cause contact dermatitis. [12] [13] [14] [15] Menthol and some others produce a feeling of cold followed by a sense of burning.

In Australia essential oils (mainly eucalyptus) have been increasingly causing cases of poisoning, mostly of children. In the period 2014–2018, there were 4,412 poisoning incidents reported in New South Wales. [16]

Use in aromatherapy

Essential oils are used in aromatherapy as part of, for example, essential oil diffusers. Reed diffuser.jpg
Essential oils are used in aromatherapy as part of, for example, essential oil diffusers.

Aromatherapy is a form of alternative medicine in which healing effects are ascribed to the aromatic compounds in essential oils and other plant extracts. Aromatherapy may be useful to induce relaxation, but there is not sufficient evidence that essential oils can effectively treat any condition. [3] Scientific research indicates that essential oils cannot treat or cure any chronic disease or other illnesses. [3] Much of the research on the use of essential oils for health purposes has serious methodological errors. In a systemic review of 201 published studies on essential oils as alternative medicines, only 10 were found to be of acceptable methodological quality, and even these 10 were still weak in reference to scientific standards. [3] Use of essential oils may cause harm including allergic reactions and skin irritation; After receiving a facial at an all-natural salon, a person experienced severe skin irritation, which highlighted the potential dangers of using "clean" beauty products marketed as being made from natural ingredients. This incident underscores the misconception that natural compounds are always safe, revealing a growing awareness within the beauty industry about the risks associated with essential oils, which can lead to allergic reactions and skin damage; [18] there has been at least one case of death. [4]

Use as pesticide

Research has shown that some essential oils have potential as a natural pesticide. In case studies, certain oils have been shown to have a variety of deterring effects on pests, specifically insects and select arthropods. [19] These effects may include repelling, inhibiting digestion, stunting growth, [20] decreasing rate of reproduction, or death of pests that consume the oil. However, the molecules within the oils that cause these effects are normally non-toxic for mammals. These specific actions of the molecules allow for widespread use of these "green" pesticides without harmful effects to anything else other than pests. [21] Essential oils that have been investigated include rose, lemon grass, lavender, thyme, peppermint, basil, cedarwood, and eucalyptus. [22]

Although they may not be the perfect replacement for all synthetic pesticides, essential oils have prospects for crop or indoor plant protection, urban pest control, [23] and marketed insect repellents, such as bug spray. Certain essential oils have been shown in studies to be comparable, if not exceeding, in effectiveness to DEET, which is currently marketed as the most effective mosquito repellent. Although essential oils are effective as pesticides when first applied in uses such as mosquito repellent applied to the skin, it is only effective in the vapor stage. Since this stage is relatively short-lived, creams and polymer mixtures are used in order to elongate the vapor period of effective repellency. [19]

In any form, using essential oils as green pesticides rather than synthetic pesticides has ecological benefits such as decreased residual actions. [22] In addition, increased use of essential oils as pest control could have not only ecological, but economical benefits as the essential oil market diversifies [21] and popularity increases among organic farmers and environmentally conscious consumers. [20] As of 2012 some EOs are authorized, and in use, in the European Union: Melaleuca oil as a fungicide, citronella oil as a herbicide, Syzygium aromaticum oil as a fungicide and bactericide, Mentha spicata oil as a plant growth regulator; Citrus sinensis oil (only in France) for Bemisia tabaci on Cucurbita pepo and Trialeurodes vaporariorum on Solanum lycopersicum ; and approvals for oils of Thymus , C. sinensis, and Tagetes as insecticides are pending. [20]

Use in food

In relation with their food applications, although these oils have been used throughout history as food preservatives, it was in the 20th century when essential oils were considered as Generally Recognized as Safe (GRAS) by the United States’ Food and Drug Administration (FDA). [24]

GRAS substances according to the FDA [25]

Common nameBotanical name of plant source
Alfalfa Medicago sativa L.
Allspice Pimenta officinalis Lindl.
Bitter almond, free from cyanide [26] Prunus amygdalus Batsch, Prunus armeniaca L., or Prunus persica (L.) Batsch.
Ambrette (seed)Hibiscus moschatus Moench.
Angelica root Angelica archangelica L.
Angelica seed
Angelica stem
Angostura (cusparia bark)Galipea officinalis Hancock, Angostura trifoliata
Anise Pimpinella anisum L.
Asafetida Ferula assa-foetida L. and related spp. of Ferula
Balm (lemon balm)Melissa officinalis L.
Balsam of Peru Myroxylon pereirae Klotzsch.
Basil Ocimum basilicum L.
Bay leaves Laurus nobilis L.
Bay (myrcia oil) Pimenta racemosa (Mill.) J. W. Moore.
Bergamot (bergamot orange)Citrus aurantium L. subsp. bergamia Wright et Arn.
Bitter almond (free from prussic acid)Prunus amygdalus Batsch, Prunus armeniaca L., or Prunus persica (L.) Batsch.
Bois de rose Aniba rosaeodora Ducke.
Cacao Theobroma cacao L.
Camomile (chamomile) flowers, German or HungarianMatricaria chamomilla L.
Camomile (chamomile) flowers, Roman or EnglishAnthemis nobilis L.
Cananga Cananga odorata Hook. f. and Thoms.
Capsicum Capsicum frutescens L. and Capsicum annuum L.
Caraway Carum carvi L.
Cardamom seed (cardamon)Elettaria cardamomum Maton.
Carob bean Ceratonia siliqua L.
Carrot Daucus carota L.
Cascarilla bark Croton eluteria Benn.
Cassia bark, Chinese Cinnamomum cassia Blume.
Cassia bark, Padang or Batavia Cinnamomum burmanni Blume.
Cassia bark, Saigon Cinnamomum loureirii Nees.
Celery seed Apium graveolens L.
Cherry, wild, barkPrunus serotina Ehrh.
Chervil Anthriscus cerefolium (L.) Hoffm.
Chicory Cichorium intybus L.
Cinnamon bark, Ceylon Cinnamomum zeylanicum Nees.
Cinnamon bark, Chinese Cinnamomum cassia Blume.
Cinnamon bark, Saigon Cinnamomum loureirii Nees.
Cinnamon leaf, Ceylon Cinnamomum zeylanicum Nees.
Cinnamon leaf, ChineseCinnamomum cassia Blume.
Cinnamon leaf, SaigonCinnamomum loureirii Nees.
Citronella Cymbopogon nardus Rendle.
Citrus peels Citrus spp.
Clary (clary sage)Salvia sclarea L.
Clover Trifolium spp.
Coca (decocainized)Erythroxylum coca Lam. and other spp. of Erythroxylum
Coffee Coffea spp.
Cola nut Cola acuminata Schott and Endl., and other spp. of Cola
Coriander Coriandrum sativum L.
Cumin (cummin)Cuminum cyminum L.
Curaçao orange peel (orange, bitter peel)Citrus aurantium L.
Cusparia barkGalipea officinalis Hancock
Dandelion Taraxacum officinale Weber and Taraxacum laevigatum DC.
Dandelion root
Dog grass (quackgrass, triticum)Agropyron repens (L.) Beauv.
Elder flowersSambucus canadensis L. and Sambucus nigra I.
Estragole (esdragol, esdragon, tarragon)Artemisia dracunculus L.
Estragon (tarragon)
Fennel, sweetFoeniculum vulgare Mill.
Fenugreek Trigonella foenum-graecum L.
Galanga (galangal)Alpinia officinarum Hance.
Geranium Pelargonium spp.
Geranium, East IndianCymbopogon martini Stapf.
Geranium, rosePelargonium graveolens L'Her.
Ginger Zingiber officinale Rosc.
Grapefruit Citrus paradisi Macf.
Guava Psidium spp.
Hickory barkCarya spp.
Horehound (hoarhound)Marrubium vulgare L.
Hops Humulus lupulus L.
Horsemint Monarda punctata L.
Hyssop Hyssopus officinalis L.
Immortelle Helichrysum augustifolium DC.
Jasmine Jasminum officinale L. and other spp. of Jasminum
Juniper (berries)Juniperus communis L.
Kola nut Cola acuminata Schott and Endl., and other spp. of Cola
Laurel berriesLaurus nobilis L.
Laurel leavesLaurus spp.
Lavender Lavandula officinalis Chaix
Lavender, spikeLavandula latifolia Vill.
Lavandin Hybrids between Lavandula officinalis Chaix and Lavandula latifolin Vill.
Lemon Citrus limon (L.) Burm. f.
Lemon balm (see balm)Melissa officinalis L.
Lemongrass Cymbopogon citratus DC. and Cymbopogon lexuosus Stapf.
Lemon peelCitrus limon (L.) Burm. f.
Lime Citrus aurantifolia Swingle.
Linden flowersTilia spp.
Locust bean Ceratonia siliqua L,
Lupulin Humulus lupulus L.
Mace Myristica fragrans Houtt.
MandarinCitrus reticulata Blanco.
Marjoram, sweetMajorana hortensis Moench.
Mate, yerba Ilex paraguariensis St. Hil.
Melissa (see balm)
Menthol Mentha spp.
Menthyl acetate
Molasses (extract)Saccharum officinarum L.
Mustard Brassica spp.
Naringin Citrus paradisi Macf.
Neroli, bigarade Citrus aurantium L.
Nutmeg Myristica fragrans Houtt.
Onion Allium cepa L.
Orange, bitter, flowersCitrus aurantium L.
Orange, bitter, peel
Orange leafCitrus sinensis (L.) Osbeck.
Orange, sweet
Orange, sweet, flowers
Orange, sweet, peel
Origanum Origanum spp.
Palmarosa Cymbopogon martini Stapf.
Paprika Capsicum annuum L.
Parsley Petroselinum crispum (Mill.) Mansf.
Pepper, black Piper nigrum L.
Pepper, white
Peppermint Mentha piperita L.
Peruvian balsam Myroxylon pereirae Klotzsch.
Petitgrain Citrus aurantium L.
Petitgrain lemonCitrus limon (L.) Burm. f.
Petitgrain mandarin or tangerineCitrus reticulata Blanco.
Pimenta Pimenta officinalis Lindl.
Pimenta leaf
Pipsissewa leaves Chimaphila umbellata Nutt.
Pomegranate Punica granatum L.
Prickly ash bark Xanthoxylum (or Zanthoxylum) americanum Mill. or Xanthoxylum clava-herculis L.
Rose absoluteRosa alba L., Rosa centifolia L., Rosa damascena Mill., Rosa gallica L., and vars. of these spp.
Rose (otto of roses, attar of roses)
Rose buds
Rose flowers
Rose fruit (hips)
Rose geraniumPelargonium graveolens L'Her.
Rose leavesRosa spp.
Rosemary Rosmarinus officinalis L.
Saffron Crocus sativus L.
Sage Salvia officinalis L.
Sage, GreekSalvia triloba L.
Sage, Spanish Salvia officinalis subsp. lavandulifolia (Vahl) Gams
St. John's bread Ceratonia siliqua L.
Savory, summer Satureia hortensis L.
Savory, winterSatureia montana L.
Schinus molle Schinus molle L.
Sloe berries (blackthorn berries)Prunus spinosa L.
Spearmint Mentha spicata L.
Spike lavender Lavandula latifolia Vill.
Tamarind Tamarindus indica L.
Tangerine Citrus reticulata Blanco.
Tarragon Artemisia dracunculus L.
Tea Thea sinensis L.
Thyme Thymus vulgaris L. and Thymus zygis var. gracilis Boiss.
Thyme, white
Thyme, wild or creepingThymus serpyllum L.
Triticum (see dog grass)Elymus repens
Tuberose Polianthes tuberosa L.
Turmeric Curcuma longa L.
Vanilla Vanilla planifolia Andr. or Vanilla tahitensis J. W. Moore.
Violet flowers Viola odorata L.
Violet leaves
Violet leaves absolute
Wild cherry bark Prunus serotina Ehrh.
Ylang-ylang Cananga odorata Hook. f. and Thoms.
Zedoary bark Curcuma zedoaria Rosc.

As antimicrobials

The most commonly used essential oils with antimicrobial action are: β-caryophyllene, eugenol, eugenol acetate, carvacrol, linalool, thymol, geraniol, geranyl acetate, bicyclogermacrene, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, viridiflorol, limonene, (Z)-linalool oxide, α-pinene, p-cymene, (E)-caryophyllene, γ-terpinene. [27]

Some essential oils are effective antimicrobials and have been evaluated for food incorporation in vitro. However, actual deployment is rare because much higher concentrations are required in real foods. Some or all of this lower effectiveness is due to large differences between culture medium and foods in chemistry (especially lipid content), viscosity, and duration of inoculation/storage. [27]

Dilution

Essential oils are usually lipophilic (literally: "oil-loving") compounds that are immiscible (not miscible) with water. They can be diluted in solvents like pure ethanol and polyethylene glycol.[ citation needed ]

Raw materials

Essential oils are derived from sections of plants. Some plants, like the bitter orange, are sources of several types of essential oil.

Bark
Berries
Flowers
Leaves
Peel
Resin
Rhizome
Roots
Seeds
Woods

Balsam of Peru

Balsam of Peru, an essential oil derived from Myroxylon plants, is used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in animal care products. [28] However, national and international surveys identified balsam of Peru among the "top five" allergens most commonly causing patch test allergic reactions in people referred to dermatology clinics. [29] [30] [31]

Garlic oil

Garlic oil is an essential oil derived from garlic. [32]

Eucalyptus oil

Most eucalyptus oil on the market is produced from the leaves of Eucalyptus globulus. Steam-distilled eucalyptus oil is used throughout Asia, Africa, Latin America and South America as a primary cleaning/disinfecting agent added to soaped mop and countertop cleaning solutions; it also possesses insect and limited vermin control properties. [33] Note, however, there are hundreds of species of eucalyptus, and perhaps some dozens are used to various extents as sources of essential oils. Not only do the products of different species differ greatly in characteristics and effects, but also the products of the very same tree can vary grossly. [34]

Lavender oil

Lavender essential oil sold at a market in France Marches des Producteurs de Pays 11 16 14.jpg
Lavender essential oil sold at a market in France

Lavender oil has long been used in the production of perfume. [35] However, studies have shown it can be estrogenic and antiandrogenic, causing problems for prepubescent boys and pregnant women, in particular. [36] Lavender essential oil is also used as an insect repellent. [37]

Rose oil

Rose oil is 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".

Toxicity

The potential toxicity of essential oil is related to its level or grade of purity, and to the toxicity of specific chemical components of the oil. [5] Many essential oils are designed exclusively for their aroma-therapeutic quality; these essential oils generally should not be applied directly to the skin in their undiluted form. [5] Some can cause severe irritation, provoke an allergic reaction and, over time, prove toxic to the liver. If ingested or rubbed into the skin, essential oils can be highly poisonous, causing confusion, choking, loss of muscle coordination, difficulty in breathing, pneumonia, seizures, and possibly severe allergic reactions or coma. [5]

Some essential oils, including many of the citrus peel oils, are photosensitizers, increasing vulnerability of the skin to sunlight. [38]

Industrial users of essential oils should consult the safety data sheets to determine the hazards and handling requirements of particular oils. [5] Even certain therapeutic-grade oils can pose potential threats to individuals with epilepsy or pregnant women.

Essential oil use in children can pose a danger when misused because of their thin skin and immature livers. This might cause them to be more susceptible to toxic effects than adults. [5]

Flammability

The flash point of each essential oil is different. Many of the common essential oils, such as tea tree, lavender, and citrus oils, are classed as Class 3 Flammable Liquids, as they have a flash point of 50–60 °C.

Gynecomastia

Estrogenic and antiandrogenic activity have been reported by in vitro study of tea tree oil and lavender essential oils. Two published sets of case reports suggest that lavender oil may be implicated in some cases of gynecomastia, an abnormal breast tissue growth in prepubescent boys. [39] [40] The European Commission's Scientific Committee on Consumer Safety dismissed the claims against tea tree oil as implausible, but did not comment on lavender oil. [41] In 2018, a BBC report on a study stated that tea tree and lavender oils contain eight substances that when tested in tissue culture experiments, increasing the level of estrogen and decreasing the level of testosterone. Some of the substances are found in "at least 65 other essential oils". The study did not include animal or human testing. [42]

Handling

Exposure to essential oils may cause contact dermatitis. [13] [14] [15] Essential oils can be aggressive toward rubbers and plastics, so care must be taken in choosing the correct handling equipment. Glass syringes are often used, but have coarse volumetric graduations. Chemistry syringes are ideal, as they resist essential oils, are long enough to enter deep vessels, and have fine graduations, facilitating quality control. Unlike traditional pipettes, which have difficulty handling viscous fluids, the chemistry syringe, also known as a positive displacement pipette, has a seal and piston arrangement which slides inside the pipette, wiping the essential oil off the pipette wall.

Ingestion

Some essential oils qualify as GRAS flavoring agents for use in foods, beverages, and confectioneries according to strict good manufacturing practice and flavorist standards. [25] Pharmacopoeia standards for medicinal oils should be heeded. Some oils can be toxic to some domestic animals, cats in particular. [43] The internal use of essential oils can pose hazards to pregnant women, as some can be abortifacients in dose 0.5–10 mL, and thus should not be used during pregnancy.[ citation needed ]

Pesticide residues

Concern about pesticide residues in essential oils, particularly those used therapeutically, means many practitioners of aromatherapy buy organically produced oils. Not only are pesticides present in trace quantities, but also the oils themselves are used in tiny quantities and usually in high dilutions. Where there is a concern about pesticide residues in food essential oils, such as mint or orange oils, the proper criterion is not solely whether the material is organically produced, but whether it meets the government standards based on actual analysis of its pesticide content. [44]

Pregnancy

Some essential oils may contain impurities and additives that may be harmful to pregnant women. [45] Certain essential oils are safe to use during pregnancy, but care must be taken when selecting quality and brand. Sensitivity to certain smells may cause pregnant women to have adverse side effects with essential oil use, such as headache, vertigo, and nausea. Pregnant women often report an abnormal sensitivity to smells and taste, [46] and essential oils can cause irritation and nausea when ingested. [5]

Toxicology

The following table lists the LD50 or median lethal dose for common oils; this is the dose required to kill half the members of a tested animal population. LD50 is intended as a guideline only, and reported values can vary widely due to differences in tested species and testing conditions. [47]

Common NameOral LD50Dermal LD50Notes
Neem14 g/kg>2 g/kg
Lemon myrtle2.43 g/kg2.25 g/kg
Frankincense>5 g/kg>5 g/kgBoswellia carterii
Frankincense>2 g/kg>2 g/kgBoswellia sacra
Indian frankincense>2 g/kg>2 g/kgBoswellia serrata
Ylang-ylang>5 g/kg>5 g/kg
Cedarwood>5 g/kg>5 g/kg
Roman chamomile>5 g/kg>5 g/kg
White camphor>5 g/kg>5 g/kgCinnamomum camphora, extracted from leaves
Yellow camphor3.73 g/kg>5 g/kgCinnamomum camphora, extracted from bark
Hot oil3.80 g/kg>5 g/kgCinnamomum camphora, oil extracted from leaves
Cassia2.80 g/kg0.32 g/kg

Standardization of derived products

In 2002, ISO published ISO 4720 in which the botanical names of the relevant plants are standardized. [48] The rest of the standards with regards to this topic can be found in the section of ICS 71.100.60 [49]

History

The resins of aromatics and plant extracts were retained to produce traditional medicines and scented preparations, such as perfumes and incense, including frankincense, myrrh, cedarwood, juniper berry and cinnamon in ancient Egypt may have contained essential oils. [50] [51] In 1923, when archaeologists opened Pharaoh Tutankhamun’s tomb, they found 50 alabaster jars of essential oils. [51] [ dubious – discuss ]

Essential oils have been used in folk medicine over centuries. The Persian physician Ibn Sina, known as Avicenna in Europe, was first to derive the fragrance of flowers from distillation, [52] while the earliest recorded mention of the techniques and methods used to produce essential oils may be Ibn al-Baitar (1188–1248), an Arab Al-Andalusian (Muslim Spain) physician, pharmacist and chemist. [53]

Rather than refer to essential oils themselves, modern works typically discuss specific chemical compounds of which the essential oils are composed, such as referring to methyl salicylate rather than "oil of wintergreen". [54] [55]

Essential oils are used in aromatherapy, a branch of alternative medicine that uses essential oils and other aromatic compounds. [56] Oils are volatilized, diluted in a carrier oil and used in massage, diffused in the air by a nebulizer or diffuser, heated over a candle flame, or burned as incense.

See also

Related Research Articles

<span class="mw-page-title-main">Cedar oil</span> Essential oil

Cedar oil, also known as cedarwood oil, is an essential oil derived from various types of conifers, most in the pine or cypress botanical families. It is produced from the foliage, and sometimes the wood, roots, and stumps left after logging of trees for timber. It has many uses in art, industry, and perfumery, and while the characteristics of oils derived from various species may vary, all have some degree of pesticidal effects.

<i>Cymbopogon</i> Genus of grasses

Cymbopogon, also known as lemongrass, barbed wire grass, silky heads, oily heads, Cochin grass, Malabar grass, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some species are commonly cultivated as culinary and medicinal herbs because of their scent, resembling that of lemons . The name Cymbopogon derives from the Greek words kymbe and pogon "which mean [that] in most species, the hairy spikelets project from boat-shaped spathes." Lemongrass and its oil are believed to possess therapeutic properties.

<span class="mw-page-title-main">Lavender oil</span> Essential oil distilled from lavender flower spikes

Lavender oil is an essential oil obtained by distillation from the flower spikes of certain species of lavender. There are over 400 types of lavender worldwide with different scents and qualities. Two forms of lavender oil are distinguished, lavender flower oil, a colorless oil, insoluble in water, having a density of 0.885 g/mL; and lavender spike oil, a distillate from the herb Lavandula latifolia, having a density of 0.905 g/mL. Like all essential oils, it is not a pure compound; it is a complex mixture of phytochemicals, including linalool and linalyl acetate.

<span class="mw-page-title-main">Tea tree oil</span> Essential oil derived from leaves

Tea tree oil, also known as melaleuca oil, is an essential oil with a fresh, camphoraceous odor and a colour that ranges from pale yellow to nearly colourless and clear. It is derived from the leaves of the tea tree, Melaleuca alternifolia, native to southeast Queensland and the northeast coast of New South Wales, Australia. The oil comprises many constituent chemicals, and its composition changes if it is exposed to air and oxidizes. Commercial use of tea tree oil began in the 1920s, pioneered by the entrepreneur Arthur Penfold.

<span class="mw-page-title-main">Thymol</span> Chemical compound found in plants including thyme

Thymol, C10H14O, is a natural monoterpenoid phenol derivative of p-Cymene, isomeric with carvacrol, found in oil of thyme, and extracted from Thymus vulgaris, ajwain, and various other plants as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. Thymol also provides the distinctive, strong flavor of the culinary herb thyme, also produced from T. vulgaris. Thymol is only slightly soluble in water at neutral pH, but it is extremely soluble in alcohols and other organic solvents. It is also soluble in strongly alkaline aqueous solutions due to deprotonation of the phenol. Its dissociation constant (pKa) is 10.59±0.10. Thymol absorbs maximum UV radiation at 274 nm.

<span class="mw-page-title-main">Absolute (perfumery)</span>

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.

<span class="mw-page-title-main">Neem oil</span> Vegetable oil from the Indian neem tree

Neem oil, also known as margosa oil, is a vegetable oil pressed from the fruits and seeds of the neem, a tree which is indigenous to the Indian subcontinent and has been introduced to many other areas in the tropics. It is the most important of the commercially available products of neem, and its chemical properties have found widespread use as a pesticide in organic farming.

<span class="mw-page-title-main">Insect repellent</span> Substance which repels insects

An insect repellent is a substance applied to the skin, clothing, or other surfaces to discourage insects from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and ticks (arachnids).

<span class="mw-page-title-main">Cajeput tree</span> Common name for several species of tree

Cajeput tree is a common name used for a certain classification of tree that has a white spongy bark that is flexible and can easily flake off the trunk. The cajeput tree is of the genus Melaleuca, native to Australia and is commonly known in North America as the tea tree. The name 'cajeput tree' is primarily used for the species M. cajuputi, M. leucadendra, M. linariifolia, M. viridiflora and M. quinquenervia. Other names for these trees are the paperbark tree, punk tree, or the white bottlebrush tree. Similar subtropical trees from the eucalyptus family are evergreens with pointed leaves and white, red or green flowers.

<span class="mw-page-title-main">Eucalyptol</span> Chemical compound

Eucalyptol is a monoterpenoid colorless liquid, and a bicyclic ether. It has a fresh camphor-like odor and a spicy, cooling taste. It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up about 70–90% of eucalyptus oil. Eucalyptol forms crystalline adducts with hydrohalic acids, o-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.

<span class="mw-page-title-main">Orange oil</span> Essential oil produced in rind of oranges

Orange oil is an essential oil produced by cells within the rind of an orange fruit. In contrast to most essential oils, it is extracted as a by-product of orange juice production by centrifugation, producing a cold-pressed oil. It is composed of mostly d-limonene, and is often used in place of pure d-limonene. D-limonene can be extracted from the oil by distillation.

<span class="mw-page-title-main">Eucalyptus oil</span> Distilled oil from the leaf of Eucalyptus

Eucalyptus oil is the generic name for distilled oil from the leaves of Eucalyptus, a genus of the plant family Myrtaceae, mostly native to Australia but cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring and fragrance, as well as having industrial uses. The leaves of selected Eucalyptus species are steam distilled to extract eucalyptus oil.

<span class="mw-page-title-main">Cannabis flower essential oil</span> Essential oil obtained from the hemp plant

Cannabis flower essential oil, also known as hemp essential oil, is an essential oil obtained by steam distillation from the flowers, panicles, stem, and upper leaves of the hemp plant. Hemp essential oil is distinct from hemp seed oil and hash oil: the former is a vegetable oil that is cold-pressed from the seeds of low-THC varieties of hemp, the latter is a THC-rich extract of dried female hemp flowers (marijuana) or resin (hashish).

<span class="mw-page-title-main">Herbal distillate</span> Aqueous product of the hydrodistillation of volatile organic substances

Herbal distillates, also known as floral waters, hydrosols, hydrolates, herbal waters, and essential waters, are aqueous products of hydrodistillation. They are colloidal suspensions of essential oils as well as water-soluble components obtained by steam distillation or hydrodistillation from plants and herbs. These herbal distillates have uses as flavorings and cosmetics. Common herbal distillates for skincare include rose water, orange flower water, and witch hazel. Rosemary, oregano, and thyme are hydrosols that may be used in food manufacturing industries.

<i>Kaempferia galanga</i> Species of flowering plant

Kaempferia galanga, commonly known as kencur, aromatic ginger, sand ginger, cutcherry, is a monocotyledonous plant in the ginger family, and one of four plants called galangal. It is found primarily in open areas in Indonesia, southern China, Taiwan, Cambodia, and India, but is also widely cultivated throughout Southeast Asia.

<i>Cymbopogon citratus</i> Species of plant

Cymbopogon citratus, commonly known as West Indian lemon grass or simply lemon grass, is a tropical plant native to South Asia and Maritime Southeast Asia and introduced to many tropical regions.

<i>Cymbopogon martinii</i> Species of grass

Cymbopogon martinii is a species of grass in the genus Cymbopogon (lemongrasses) native to India and Indochina but widely cultivated in many places for its aromatic oil. It is best known by the common name palmarosa as it smells sweet and rose-like. Other common names include Indian geranium, gingergrass, rosha, and rosha grass.

<span class="mw-page-title-main">Aromatherapy</span> Alternative medicine practice

Aromatherapy is a practice based on the use of aromatic materials, including essential oils and other aroma compounds, with claims for improving psychological well-being. It is used as a complementary therapy or as a form of alternative medicine, and typically is used via inhalation and not by ingestion.

<span class="mw-page-title-main">Bergamot essential oil</span> Cold-pressed essential oil

Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavouring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note.

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