Methods of Extracting Pure Aromatic Oils

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http://www.naturesgift.com/extraction.htm

 

Methods of Extracting Oils

 

Distillation:

The vast majority of true essential oils are produced by

distillation. There are different processes used, however. In all of

them, water is heated to produce steam, which carries the most

volatile chemical of the aromatic material with it. The steam is then

chilled (in a condenser) and the resulting distillate is collected.

The Essential Oil will normally float on top of the Hydrosol (the

distilled water component) and may be separated off.

 

 

Steam Distillation

True Steam distillation uses an outside source of steam which pipes

the steam into the distillation unit, sometimes at high pressure. The

steam passes through the aromatic material, and exits into the

condensor.

 

Hydrodistillation

The botanicals are fully submerged in water, producing a " soup " , the

steam of which contains the aromatic plant molecules. This is the

most ancient method of distillation and the most versatile. It's the

method most often used in primitive countries. The risk, of course,

is that the still can run dry, or be overheated, burning the

aromatics and resulting in an EO with a burnt smell.

Hydrodistillation seems to work best for powders (ie, spice powders,

ground wood, etc.) and very tough materials like roots, wood, or

nuts.

 

Water & steam distillation

A water and steam distillation arrangement can be compared to a

kitchen steamer basket, with the botanicals supported in a " basket "

over boiling water, thus exposing the plant material only to the

rising steam vapors. This is the best method for distilling leafy

materials, but doesn't work well for woods, roots, seeds, etc.

 

Absolutes and Concretes: Solvent Extraction

Very delicate aromatics, Jasmine, Linden Blossom,etc. can not survive

the process of distillation. To capture their magical aromas, a

process of solvent extraction is used.

An extracting unit is loaded with perforated trays of blossoms. The

blossoms are washed repeatedly with a solvent (usually hexane.) The

solvent dissolves all extractable matter from the plant whch includes

non-aromatic waxes, pigments and highly volatile aromatic molecules.

The solution containing both solvent and dissolvable plant material

is filtered and the filterate subjected to low pressure distillation

to recover the solvent for further use. The remaining waxy mass is

what is called the concrete and it contains in the case of J.

grandiflorum as much as 55% of the volatile oil.

 

The concentrated concretes are processed further to remove the waxy

materials which dilute the pure essential oil. To prepare the

absolute from the concrete, the waxy concrete is warmed and stirred

with alcohol (usually ethanol.). During the heating and stirring

process the concrete breaks up into minute globules. Since the

aromatic molecules are more soluble in alcohol than is the wax an

efficient separation of the two takes place. But along with the

aromatic molecules a certain amount of wax also becomes dissolved and

this can only be removed by agitating and freezing the solution at

very low temperatures(around -30 degrees F) In this way most of the

wax precipates out. As a final precaution the purified solution is

cold filtered leaving only the wax-free material (the absolute.)

 

This solvent extraction actually yields three usable products; first

the concrete (as in rose concrete, my favorite solid perfume), the

precious absolutes, and the floral waxes, for addition to candles,

thickening creams and lotions as a softly floral scented alternative

to beeswax.

 

Carbon Dioxide Extraction

When CO2 (carbon dioxide) is subjected to high pressure, the gas

turns into liquid. This liquid CO2 can be used as a very inert,

safe, " liquid solvent. " which will extract the aromatic molecules in

a process similar to that used to extract absolutes (above.) The

advantage, of course, is that no solvent residue remains, since at

normal pressure and temperature, the CO2 simply reverts to a gas and

evaporates.

CO2 extraction has given us essences of some aromatics that don't

yield essential oils, Rose Hip Seed, and Calendula, for examples. In

my experience (or opinion!) if the same essential oil is available

both as a steam distilled EO and a CO2 extracted essence, the CO2

seems to have a richer, more intense scent, since more of the

aromatic chemicals are released through this process.

 

Cold Pressing

We are all familiar with the spray of orange essential oil that can

be released by scoring or zesting the skin of the fruit. The cold

pressed citrus oils are commercial produced just this way, by

machines which score the rind and capture the resulting oil. Although

many citrus oils are also produced by steam distillation, they seem

to lack the vibrancy of the cold pressed oils.

 

Florasols/Phytols

This extraction method uses a new type of benign gaseous solvents. In

the late 1980s Dr. Peter Wilde first recognized the unique properties

of these solvents for the extraction of aromatic oils and

biologically active components from plant materials, for use in the

food, pharmaceutical, aromatherapy and perfume industries. " Florasol "

(R134a), is the solvent upon which the process is based

Extraction occurs at or below ambient temperatures,hence there is no

thermal degradation of the products. The extraction process utilizes

the selectivity of the solvent and produces a free flowing clear oil

free of waxes.

 

At the current time, the sole US distributor of Dr. Wilde's Florasols

is The Essential Oil Company. However, we are researching a source

for bulk Florasols at a more appealing price.