Aromatherapy Secrets

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Aromatherapy Secrets

 

Production of Essential Oils

There are a number of methods used to obtain essential oils from the

plants. The part of the plant used varies, due to concentration of

the oil in the cells. All parts contain some oil, but the plants are

processed according to the type of plant.

 

As an example:

 

Blossoms - Jasmine oil comes from the blossoms.

 

Wood - Sandalwood comes from the wood.

 

Root - Carrot comes from the root

The basic process is designed to break down the cellular walls and to

release the essential oil. The following methods are the most common

methods used to extract essential oil

 

Distillation

Distillation is a process of heating a substance until its more

volatile constituents pass into the vapor phase, and then cooling the

vapor to recover such constituents in liquid form by condensation.

The main purpose of distillation is to separate a mixture of several

components by taking advantage of their different volatility's, or

the separation of volatile materials from nonvolatile materials.

Distillation is the main method by which essential oils are extracted

from plants. There are two methods of distillation.

 

The term " still " , is the vessel in which liquids are boiled during

distillation. Stills for laboratory work are usually made of glass,

but industrial stills are generally made of iron or steel. In cases

in which iron would contaminate the product, copper is often used.

 

If two insoluble liquids are heated, each is unaffected by the

presence of the other and vaporizes to an extent determined only by

its own volatility. Such a mixture, therefore, always boils at a

temperature lower than that of either constituent. The percentage of

each constituent in the vapor depends only on its vapor pressure at

this temperature. This principle may be applied to substances such as

oils that would be damaged by overheating if distilled in the usual

fashion.

 

Steam Distillation

Direct - Involves placing the plant material in water which is then

heated and brought to boil.

 

Steam - Involves placing the plant material on a rack or grid and

heating the water above or beneath it. The steam passes through the

plant matter, causing the Aromatic volatile essence held within the

plant to be released.

 

In both methods, the heat and steam cause the walls of plant cells to

break down and release the essence in the form of vapor. The steam

and essence passes through a pipe, which passes through cooling

tanks. This causes steam and essence to return to a liquid form. That

liquid is collected in vats. The steam condenses into a watery

distillate while the essence from the plant becomes an essential oil.

This oil being lighter than water, collects in the upper part of the

vat and can be easily separated. In some cases, the water is sold as

flower or herbal water.

 

Vacuum Distillation

This method is rarely used and is included for your information only.

It is used on occasion and you should be aware of it. It is generally

a more expensive process. Another method of distilling substances at

temperatures below their normal boiling point is to partially

evacuate the still. This method is as effective as steam

distillation, but somewhat more expensive. The greater the degree of

vacuum, the lower is the distillation temperature. If the

distillation occurs in a near vacuum, the process is called molecular

distillation. The process is used industrially for the purification

of vitamins and other items. The substance is placed on a plate in an

evacuated space and heated. The condenser is a cold plate, placed as

close to the first as possible. Most of the material passes across

the space between the two plates, and very little is lost.

 

Maceration

Maceration is to separate constituents by soaking. There are two

methods used in the maceration process.

 

One method is the preparing of aromatic plants by prolonged soaking

in warm water or oil creating an infusion. The plant material is

filtered out. The resulting liquid contains the essential oil. When

water was used, it is used as 'a wash " . If oil is used to soak the

plant matter, it is used as an infusion oil e.g. Calendula oil.

 

The second method is dipping the blossoms into hot oil until the wall

of the cells break apart. The hot oil absorbs the essence. The oil is

then cooled and separated. This is an old and expensive method not

often used today.

 

Pressing

Pressing is simply the pressing of the plant material until the

essences drain. Control is important however, so that the temperature

does not exceed set standards.

 

Essential Oil of citrus fruits, such as orange, lemon, grapefruit and

tangerine, are obtained by pressing the unpolluted peels of the

fruit. The peel is pressed between two pieces of wood, one of which

has a sponge attached to it. The oil is released by the cells and

absorbed by the sponge. Wringing out the sponge then collects the

oil. This type of essence is high quality and suitable for internal

use.

 

Enfluerage / Extraction

This is a process in which odourless fats or oils absorb the

fragrance of fresh flowers. This method is used to produce an

absolute. Some of the finest flower absolutes are produced by means

of solvent extraction. Extraction is reserved for plants with a low

concentration of Essential Oil like Jasmine. These oils usually have

a finer fragrance. There are two methods used to extract the

Essential Oil.

 

In the first, the blossoms are spread on perforated metal sheets and

washed continuously with the same water until all Essential Oils are

dissolved. Afterwards, the Essential Oils are separated from the

water by distillation.

 

In the second method, both enfluerage and maceration depend on the

physical fact that fat will absorb the essential oils within the

plant. A sheet of glass is placed into a wooden frame and coated with

a thin layer of fat. Freshly picked flowers are spread over the fat.

After 24 hours the flowers will have given up all their oils to the

fat and the dried and withered flowers are removed. The process is

then repeated. This process is continued for up to three months. When

the fat has been completely saturated with the essential oil, the fat

is then collected and cleared of any debris. The resulting mixture is

known as pomade. The essential oils of the flowers are isolated from

the pomade with a solvent, such as petrol ether. After the solvent

has evaporated, a paste remains called a " concrete " . This paste also

contains waxes and chlorophyll, and is only partly soluble in

alcohol. The paste is mixed with alcohol, heated to 120 degrees

Fahrenheit, cooled again, and filtered. The remaining alcohol is

removed through evaporation. Finally, an oily residue remains that is

totally soluble in alcohol.

 

The residue or concrete is then diluted in alcohol and shaken

vigorously for twenty-four hours to separate the fat from the

essential oils. The alcohol absorbs the essential oil from the fat.

The alcohol is then evaporated, leaving the very concentrated

essential oil. They are not suitable for internal use. (If not

separated, the fats are used for cosmetics such as high quality

creams, called " huiles francaises'.

 

A large number of flowers is needed to produce a small amount of

essential oil. It takes 1000 pounds of petals to make approximately

two pounds of rose oil. This equates to 30 roses to make one drop of

essential oil. This is a very expensive and time-consuming process

that accounts for the high price of these oils or absolutes. Today,

extraction is done using carbon dioxide, a liquid gas. This allows

the process to be carried out with low temperatures. This preserves

the quality of a very fragile fragrance, like the Lily of the Valley.

The use of carbon dioxide removes any possibility of the absolute

having any solvent contamination.

 

To avoid the higher prices of true, natural and pure Absolute oil,

trading companies often offer absolute oils that are diluted with up

to 90% vegetable oil. This does not affect or damage the healing

properties and the scent is still strong since these oils are highly

concentrated. In fact, it is recommended to use them diluted.

 

Solvent Extraction

This is a combination of processes. It is commonly used for gums and

resins, as well as flowers. Flowers are treated with petroleum, ether

or benzene. Resins and gums are treated with acetone. The plant

material is placed in a glass container and saturated with a solvent.

This is then heated electrically causing the odour bearing molecules

to evaporate, which are then filtered out and collected.

 

 2000 http://www.naturesaroma.com/info/eoproduction.htm