Essential Oil 101 (5)：Extractions of Essential Oil
An essential oil is that aromatic, volatile liquid that is within many shrubs, flowers, trees, roots, bushes, and seeds and that is usually extracted through steam distillation.
The Oldest form of Extraction - Enfleurage
One of the oldest and crudest forms of extraction was known as enfleurage. Raw plant materials such as stems, foliage, bark, or roots was crushed and mixed with olive oil, animal fat, and some vegetable oils. Cedar bark was stripped from the trunk and branches, ground into a powder, soaked with olive oil, and placed in a wool cloth. The cloth was then heated. The heat pulled the essential oil out of the bark particles into the olive oil, and the wool was pressed to extract the essential oil. Sandalwood oil was also extracted in this fashion.
Enfleurage was also used to extract essential oils from flower petals. In fact, the French word enfleurage means literally "to saturate with the perfume of flowers". For example, petals from roses or jasmine were placed in goose or goat fat. The essential oil droplets were pulled from the petals into the fat and then separated from the fat. This ancient technique was one of the most primitive forms of essential oil extraction.
Other extraction techniques include：
Soaking plant parts in boiling water
Cold-pressing
Soaking in alcohol
Steam distillation - meaning that as the steam travels upward, it saturates the plant material, causing the plant membranes containing the oil to break open and release the oil, which then becomes a vapor that travels with the steam into the condenser, where it returns to its liquid form and is then separated from the water.
Steam Distillation
Steam distillation is a separation process for materials that are temperature sensitive, like essential oils. There are three methods of steam distillation.
Simple Distillation
The plant material is loaded into the extraction chamber filled with water, which is heated to soften the plant fiber so that the oil molecules can be released.
As steam begins to rise, the oil molecules are released as vapors, which are carried with the steam into the condenser. The cooling water in the condenser converts the steam to water and the vapors to oil.
The oil and water mixture continues to flow into the separator, where the oil rises to the top of the water so that it can be drained off into containers. Clove and Nutmeg are distilled this way.
Hydrodistillation
Resinous material like Frankincense and Myrrh are extracted through the method of hydrodistillation.
The resin is immersed in boiling water that is in constant motion while steam is injected into the chamber.
The resinous gas is then released into the steam, which carries it to the condenser, where the steam and vapor are gradually cooled to a liquefied form.
The water and oil mixture travels into the separator so that the oil can flow to the top of the water and be poured off into containers.
Traditional distillation
Plant material is loaded into the extraction chamber and tightly compacted. As the boiler heats the water, steam is released into the bottom of the chamber and starts to travel upward, saturating the material.
The steam impregnates the plant fiber, causing it to release the oil molecule as a gas from the oil glands of the plant. Then the steam carries the fat to the condenser, where it goes through a phase-change condensation as it passes through the cooling process in the swan neck and liquefies into water and oil.
The water and oil mixture then flows into the separator, where the oil can rise to the top of the water to be poured off into containers.
In each of these processes as the steam rises, it carries the released oil vapor into the condenser, where the water and oil vapor convert to a liquid and flow into the separator so that the oil can rise to the top of the water and be drained off.
The Art of Distillation
Distillation is as much a science as it is an art. If the pressure or temperature is too high, or if the cooking chambers are constructed from reactive materials, the oil may not be therapeutic grade.
In ancient distillation, low pressure (5lbs or lower) and low temperature were extremely important to produce the therapeutic benefits. The late Marcel Espieu, who was president of the Lavender Growers Association in Southern France for 20 years, maintained that the best oil quality can be produced only when the pressure is zero lbs during distillation.
Temperature also has a distinct effect. At certain temperatures, the oil fragrance and chemical constituents become altered. High pressures and high temperatures seem to cause harshness in the oil. Even the oil pH and the polarity are greatly affected.
For example, Cypress requires a minimum of 24 hours of distillation at 265F and 5lbs of pressure to extract most of the therapeutically active constituents. If distillation time is cut by only 2 hours, 18-20 constituents will be missing from the resulting oil.
Master Distiller
A master distiller must oversee the entire process by harvesting at just the right time for the plant maturity and distilling with the proper temperature, pressure, and time, which varies with different plant material.
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Copyright @Naturalice Garden 2021
Source：
Life Science Products and Publishing Essential Oils Desk References (8th Edition) Life Science Products and Publishing
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