An essential oil is a chemical compound that is a concentrated form of a liquid which is hydrophobic in nature, or one that does not mix with water. These contain certain chemicals that are aromatic in nature, thus giving the essential oil and aromatic fragrance and are usually derived from plants.
Essential oils are also referred to as ethereal oils, aetherolea, volatile oils or are simply known by the name from which they are obtained or extracted, such as sandal wood oil obtained from the sandal wood plant.
The name essential oil is derived from the fact that the oil basically captures and contains the essence or smell or aroma or the fragrance of the plant from which it is prepared or derived and the same being characteristically different with each plant.
We need to differentiate the terms essential here from that used in biochemistry especially in the case of essential fatty acids or essential amino acids which provide nutrition and are required for building body muscle and tissue where as in this case, essential is only the property of the compound as has been explained above and there is no major biochemical use nor do these help in building body and muscle mass.
In order to obtain essential oils, the crude substances used must pass through a number of processes where in the oil is extracted using certain procedures such as distillation, cold pressing, extraction, filtration, tapping and sedimentation to name a few. These processes help obtain the finest grade and purest and most concentrated form of extract that can be obtained from the plant.
Essential oils find use in a variety of household products especially cosmetics where in they are used in soaps, shampoo and perfumes to name a few. They also find use in certain products used for religious procedures and rituals such as incense sticks. Lately, they have also been used to add and enhance the flavor of certain foods and are used widely in the food manufacturing industry.
The use of essential oils in history finds mention around the year 1200 where in the process to obtain the same were believed to be used by Ibn al Baitar who was a pharmacist, physician and a chemist of Al Andalusian or Muslim controlled Spain which is modern day Spain as we know it.
These oils were used for a variety of illnesses ranging from a simple skin rash to complicated disease conditions during those days. The use of essential oils was considered as an alternative medicine therapy and many a times the same was given to either inhale or the body or the affected part was massaged with a specific oil so as to obtain relief. In some documented cases, the essential oil was dispensed to the patient in a bottle that they were supposed to carry and inhale at regular intervals, these bottles would come to be known as smelling bottles.
The use of essential and aromatic oils thus during the historical periods gave birth to what we now know as modern day Aroma therapy which forms an important branch of alternative medicine and is widely used even to date.
Processes used to obtain essential oils
The mother or the crude plant substance has to go through a number of processes before the oil can be obtained and extracted.
Distillation is the commonest process where in the whole plant in the raw form is put into a machine called as a distillator which is put over water that is made to heat slowly. As a result, the steam passes over the plant carrying along with it small droplets of the volatile oils that the plant possesses, the same then condenses at the other end of the distillator from where the extract can be further concentrated and obtained.
This process is essential in obtaining oils such as eucalyptus, tea tree and lavender to name a few.
Expression is another process that was used earlier to distillation where in the peels of certain fruits and other substances were passed through a mechanically operated press where in the immense pressure applied would release the oils they contained.
This process was commonly used in cases of oils obtained from the citrus group such as orange and lemon.
Solvent Extraction is a process developed recently owing to the advances in biochemistry.
In this case, certain chemicals which act as solvents for the essential oils are used and the raw substances from which the oils have to be obtained are exposed to these solvents and then filtered. This solution is called as a concrete and is highly aromatic and concentrated in nature.
The concrete mixture is then exposed to a variety of other processes, cooling to name one where in it is cooled at extreme temperatures below negative and the various components are separated and thus obtained.
Substances commonly used are liquid carbon dioxide and ethyl alcohol which are known to be good solvents.
Flora sol Extraction has been recently developed where in a chemical called flora sol is used which is also an extremely good solvent for essential oils. The advantage that this method possesses over others is that the oils are extracted at temperatures below that of the standard room temperature, thus the substances are not exposed to higher temperatures keeping the quality and standard of the obtained essential oil to the purest that can be made available.
Medical usage and pharmacology of essential oils
The recent advances in the field of biochemistry and pharmacology we have been able to decipher and understand the action of various oils on the various systems of the body and how each plays a beneficial role to the body in its own unique way.
Oregano oil, for example contains carvacol which is known to control the growth of bacteria such as E. coli and bacillus cereus. It is known to act on their cell membranes thereby destroying the same thus controlling their growth and spread.
Similarly, thymol is another essential oil that is obtained from thyme and it is of immense medicinal use as it helps the spread of microbes in the body owing to its antimicrobial properties. It is also known to lower drug resistance especially to that of penicillin. There have been studies that have shown that these oils have cancer controlling properties and help check the spread and growth of the cancer in the body.
A certain number of oils, when taken orally or ingested have a beneficial action on the stomach as they enhance the secretion of gastric juice in the stomach which directly helps in improving and enhancing the digestive function of the stomach. Some of them also have beneficial properties lower down on the intestine as they help as anti-spasmodics and promote regular and healthy peristaltic movements essential to digestion of food and production of fecal matter.
Oils such as that obtained from Juniper have a beneficial action on the kidneys as they act as diuretics and promote the formation and expulsion of urine by the same.
A large group of oils are known to have soothing properties towards the skin and are applied locally in cases of certain skin conditions. The most famous of these is the tea tree oil that is an extract obtained from the tea tree.
As we have already mentioned above, essential oils also find use in aromatherapy, an alternative medical science used to treat certain disorders. Aromatherapy is used in cases of skin disorders, allergic reactions and is known to have a calming and soothing effect on the mind, thereby relaxing and calming the senses.
Side effects range from a minor skin reaction to liver dysfunction and the use of essential oils needs to be carried out carefully under supervision especially in those who suffer from allergies or have sensitive skin.
The oils also have varying temperatures of flammability. The most common of the lot are included and classified under the class 3 of flammable liquids as their flash point is between 50 to 60 degree centigrade. The oils classified under this include citrus, tea tree and lavender oil to name a few.
The use of certain oils should be restricted during pregnancy as they may lead from mild symptoms of nausea and vomiting to leading to an abortion as some of the oils contain abortive properties. Thus, their handling and use during pregnancy has to be under strict supervision.
Thus we can broadly understand how essential oils can be obtained, their uses and their pharmacological actions with their beneficial and harmful effects on the human body.
Further on, we shall study certain essential oils in greater detail and understand their uses and properties.