The essential oil is an oil extracted from plants which have a strong odor and undergo evaporation on exposure to normal temperature.
They are very volatile hence on the exposure they evaporate fast leaving empty residues behind. Therefore they are the essence of the flowers or fruits containing them.
They are the key components responsible for fragrance and odor of aromatic plants.
On exposure to normal temperature, these essential oils evaporate, but some of them exist as liquids (anise oil, rose oil) while some of them even as solid crystals like mentha.
Though they are termed as oils, chemically they are entirely different from natural oils obtained from plants. They are less complex and less dense than regular oils obtained from plants.
Essential oils are needed for healthy living and so they are of quite a demand in the market. Some of the important essential oils are
1. Essential oils use in Medicine:
There are many essential oils which are quite important in medicine. Some of them have a direct medical application due to inherent medicinal properties while others are used as flavoring agents, adjuvants and additives in preparation of medicinal formations like syrups, ointments, lotions, etc.
a) Essential oils with medicinal applications
Carane: It is used for its properties like antiseptic (to kill microbes), carminative (to expel gas in the stomach, stimulant (to improve mood), stomachic (increases hunger or appetite) and a diuretic (enhance urination, i.e., to minimize blood pressure and also prevent fluid accumulation)
Eugenol: It is an essential oil obtained from clove. It is used as an antiseptic, dental analgesic, tooth decay.
Eucalyptus: It is used as a nasal decongestant to relieve stuffy nose, counter-irritant, antiseptic and expectorant (to expel phlegm from respiratory tract). Primarily it is used during cough and colds to and hence incorporated in cold creams and balms.
Cineole: As an expectorant in bronchitis, tuberculosis and also as antiseptic, anesthetic (minimize or nullify pain) in inflammation.
Myrtenal leaves are frequently used as a mild diuretic, and also in liver disorders like jaundice. In latin America it is also recommended for gonorrhea like urogenital inflammations.
Menthol: It is used as a rubefacient. It mainly enhances blood circulation when applied on the skin. This helps the drug to be absorbed easily from the skin surface. Hence we see many analgesics ointments comprising of diclofenac having menthol as one of the constituents.
b) Essential oils used for medicinal formulation:
Some of the drugs possess a pungent odor which might be disagreeable to consume. Hence during the formulation of syrups, ointment, etc. essential oil are included to mask the bad odor. Some of the essential oils are also used as preservatives. Examples are eugenol, menthol, vanilla etc.
2. Essential Oils Uses for food:
Essential oils impart good and pleasant flavor when added to food stuff. Some of them are also added as preservatives and sometimes as to impart health benefits like to expel gas from the stomach (carminative) to increase appetite etc.
Some of them include fennel (due to essential oil fenchone), cardamom, etc. Vanilla is another one which is used in making ice creams, chocolates, etc. Safranal is used in confectionery.
Perillaldehyde is another essential oil which forms oxime used as a sweetening agent. It is found to be about 2000 times sweeter than sugar itself.
Citronellal is used to impart citrus flavor artificially.
To get an idea of the source of the plant producing these essential oils refer to list of medicinal plants.
3. Essential oils use in cosmetics:
Most of the essential oils used in cosmetics are for perfumes, toothpaste, soaps, facial creams, etc. They impart a pleasant odor and even antiseptic properties.
a) Citral imparts citrus flavor hence it is used in many soaps and perfumes.
Examples are Carvone used in toothpastes, mouthwashes etc. for oral hygiene and also in soaps and perfumes. It is also used in perfumes.
b) Eugenol is majorly used in toothpastes and mouthwashes due to its antimicrobial, analgesic and also flavoring properties.
c) Linalool is used in perfumes as it imparts the smell of French lavender oil. Geraniol and Geranyl Acetate are also used to scent the soaps and perfumes.
These essential oils are used in cosmetics and medicinal preparation because of their ability to mask the odors even at low concentration without disturbing the actual active ingredient in the formulation.
Ex: Myrcene, Ocimene from basil
4. Essential oils to control pests/ insects;
Citronellal is an insect repellent. Turpentine oil is used in paints as an insect repellent. Carvacrol is used as a disinfectant to clean the floors, walls and other surfaces. Furfural is used as insecticide, germicide, and fungicide. Cineole is used in room sprays. Thymol as anti-bacterial and antifungal.
5. In cold & alcoholic beverages:
Essential oils like carvone, vanilla are used in making beverages to impart a pleasant odor to preparation.