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Essential oils - Volatile Oils Classification and Its Extraction

Essential oils - Volatile Oils Classification and Its Extraction


Essential oils - Volatile Oil Classification and Its Extraction - The secondary metabolites occurring in various plant and animal families, which are also known as the essential oils because of the reason that they represent the essence of the active chemical constituent present in them. Volatile oils are also known as ethereal oils.

DEFINITION

The organic compounds are volatile principles of plant and animal sources which are evaporated when exposed to air, at ordinary or room temperature.

CLASSIFICATION OF VOLATILE OILS

The essential oils are often classified according to the natural odors of plant in which they occur, the essential oils
are classified according to their main chemical constituents, which are present in them.

1. Alcohol Volatile Oils

Peppermint, Cardamom, Rose, Sandalwood, Coriander.

2. Aldehyde Volatile Oils

Cinnamon, Lemon Peel, Orange Peel, Lemon-Grass.

3. Ester Volatile Oils

Gaultheria, Lavender, Mustard, Juhi

4. Hydrocarbon Volatile Oils

Turpentine, Black Pepper, White Pepper, Pink Pepper

5. Oxide Volatile Oils

Eucalyptus

6. Phenolic-Ether Volatile Oils

Fennel, Anise, Nutmeg

7. Phenol Volatile Oils

Clove, Thyme

FEATURES OF VOLATILE OILS

Volatile oils are naturally found in plants of about 60 different families like the following,
1. Rutaceae
2. Labiateae
3. Umbelliferae
4. Zingiberaceae
5. Lauraceae
Volatile oils are formed by specialized Secretory cells like the following,
1. Ducts
2. Cells
3. Trichomes
4. Schizogenous cavities
5. Lysigenous cavities
6. Modified parenchymatous cells

OCCURRENCE OF VOLATILE OILS

The volatile oils occur almost in all the plant parts such as the following,
1. Leaves – Lavender, Lemon-grass
2. Fruits – Coriander
3. Barks – Cinnamon, Sandalwood
4. Roots – Cyprus, Khas
5. Rhizome – Ginger, Curcuma
6. Flower – Rose, Juhi, Gaultheria

Medicinal uses of volatile oils/essential oils

1. Used as Antiseptics
2. Used as Anti-bacterial
3. Used as Disinfectants
4. Used as Carminative

EXTRACTION OF VOLATILE OILS

The volatile oils or essential oils maybe extracted from seeds, rhizomes, flowers, fruits, leaves, heartwoods, barks.
There are large no. of complex methods employed for the desirable extraction of the volatile oils not only focusing on the efficiency of the product obtained but at the same time ensuring that none of the product is deteriorated while the extraction and processing methodologies take place.
The extraction method used for each type of volatile oil maybe differing, according to their properties, the ones generally used are listed below:

A. Distillation

B. Expression method

1. Sponge method
2. Eculle (scarification) method
3. Rasping process
4. Mechanical process

C. Extraction method

1. Extraction with volatile solvents
2. Extraction with non-volatile solvents

  • Enflurage method
  • Pneumatic method
  • Maceration method

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