Aromatherapy Processing Methods

There are a number of methods used to obtain essential oils from plants. The part of the plant used varies, due to concentration of the oil in the cells - all parts contain some oil. As examples: Jasmine oil comes from the blossoms of the plant, Sandalwood comes from the wood, and 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 methods most commonly used to extract essential oil: distillation, maceration, pressing, enfleurage or solvent extraction.

Steam Distillation

Distillation is a process of heating a substance until its more volatile constituents pass into the vapor phase and then are cooled to recover such constituents in liquid form by condensation. Basically, steam softens the plant material, vaporizes the essential oils and carries them into the cooling chamber. The essential oil and the water is separated by a filter or by a centrifugal separator. Some plants need to be distilled several times to remove all the essential oil and the process can take up to 48 hours in duration.

The main purpose of distillation is to separate a mixture of several components by taking advantage of their different volatilities or the separation of volatile materials from non-volatile materials. Distillation is the main method by which essential oils are extracted from plants.

As a point of interest, if two insoluble liquids are heated, each is unaffected by the presence of the other and vaporizes to an extent determined 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 that temperature. This principle may be applied to substances such as oils that would be damaged by over heating if distilled in the usual fashion.

Maceration

Maceration is to separate constituents by soaking. There are two methods used in the maceration process.

The first method is to prepare the aromatic material by prolonged soaking in warm water or oil. The plant matter is then filtered out. The resulting liquid contains the essential oil. When water was used it is called a "wash". If oil was used it is called an "infusion".

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. Note: The dangers presented by these types of "oils" is not based only on the properties of the plant, but also on the oil it was soaked in. As an example, if peanut oil was used the resulting essential oil would be hazardous to those with a nut allergy regardless of what the plant matter was.

Pressing

Pressing is simply the pressing of the plant material until the essences are squeezed out. Control is important so that the temperature does not exceed set standards.

Essential oils of citrus fruits such as oranges, lemons, grapefruits and tangerines are obtained by pressing the peels or rinds 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 of the peel and absorbed by the sponge. The oil is then collected by wringing out the sponge. This type of essence is of a high quality.

Enfleurage/Extraction

This process is used less often, however it is still found in many areas of the world. It is a process in which odorless 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 enfleurage 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 a 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.

Solvent

This is a combination of processes. This process is commonly used for resins as well as flowers. Solvents such as hydrocarbons are used to extract the aromatic material from resin. The plant material is placed in a container and saturated with the solvent. It is then heated electrically causing the molecules to evaporate. This is then filtered.

The oils produced are not classed as essential oils. They are referred to as absolutes or resinoids. The general term "essential oil" is still commonly used however, when referring to them.

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	Aromatherapy Processing Methods There are a number of methods used to obtain essential oils from plants. The part of the plant used varies, due to concentration of the oil in the cells - all parts contain some oil. As examples: Jasmine oil comes from the blossoms of the plant, Sandalwood comes from the wood, and 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 methods most commonly used to extract essential oil: distillation, maceration, pressing, enfleurage or solvent extraction. Steam Distillation Distillation is a process of heating a substance until its more volatile constituents pass into the vapor phase and then are cooled to recover such constituents in liquid form by condensation. Basically, steam softens the plant material, vaporizes the essential oils and carries them into the cooling chamber. The essential oil and the water is separated by a filter or by a centrifugal separator. Some plants need to be distilled several times to remove all the essential oil and the process can take up to 48 hours in duration. The main purpose of distillation is to separate a mixture of several components by taking advantage of their different volatilities or the separation of volatile materials from non-volatile materials. Distillation is the main method by which essential oils are extracted from plants. As a point of interest, if two insoluble liquids are heated, each is unaffected by the presence of the other and vaporizes to an extent determined 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 that temperature. This principle may be applied to substances such as oils that would be damaged by over heating if distilled in the usual fashion. Maceration Maceration is to separate constituents by soaking. There are two methods used in the maceration process. The first method is to prepare the aromatic material by prolonged soaking in warm water or oil. The plant matter is then filtered out. The resulting liquid contains the essential oil. When water was used it is called a "wash". If oil was used it is called an "infusion". 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. Note: The dangers presented by these types of "oils" is not based only on the properties of the plant, but also on the oil it was soaked in. As an example, if peanut oil was used the resulting essential oil would be hazardous to those with a nut allergy regardless of what the plant matter was. Pressing Pressing is simply the pressing of the plant material until the essences are squeezed out. Control is important so that the temperature does not exceed set standards. Essential oils of citrus fruits such as oranges, lemons, grapefruits and tangerines are obtained by pressing the peels or rinds 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 of the peel and absorbed by the sponge. The oil is then collected by wringing out the sponge. This type of essence is of a high quality. Enfleurage/Extraction This process is used less often, however it is still found in many areas of the world. It is a process in which odorless 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 enfleurage 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 a 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. Solvent This is a combination of processes. This process is commonly used for resins as well as flowers. Solvents such as hydrocarbons are used to extract the aromatic material from resin. The plant material is placed in a container and saturated with the solvent. It is then heated electrically causing the molecules to evaporate. This is then filtered. The oils produced are not classed as essential oils. They are referred to as absolutes or resinoids. The general term "essential oil" is still commonly used however, when referring to them. Sharon (Question?) (About Sharon) (Print This)