All official volatile oils are of vegetable origin. All official volatile oils are of vegetable origin



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By methods using oils & fats

  • By extraction by supercritical gasses



    • a. SIMPLE STEAM DISTILLATION

    • Plant material is immersed directly in a still filled with water. This is then brought to a boil.

    • Heterogeneous vapours are condensed on a cold surface.

    • Essential oil separates based on difference in density and immiscibility.



    Plant does not come into contact with the water  steam is injected through the plant material placed on perforated trays.

    • Plant does not come into contact with the water  steam is injected through the plant material placed on perforated trays.

    • It is possible to operate under moderate pressure.

    • Advantages: Limits the alteration of the constituents of the oil

    • It shortens the duration of the treatment

    • It conserves energy

    • It can also be conducted on on-line in automated set ups.



    Pulses of steam is sent through the plant material at very low pressure from (top to bottom).

    • Pulses of steam is sent through the plant material at very low pressure from (top to bottom).

    • ADVANTAGE: Normally produces a product of high quality.

    • Saves time and energy.



    The rind is lacerated, and the contents of the ruptured secretory cavities are recovered.

    • The rind is lacerated, and the contents of the ruptured secretory cavities are recovered.

    • CLASSIC PROCESS: an abrasive action is applied on the surface of the fruit in a flow of water. The solid waste is eliminated, and the essential oil separated from the aqueous phase by centrifugation.

    • OTHER machines break the cavities by depression, and collect the essential oil directly  prevents the degradation linked to the action of water.



    Most facilities allow for the simultaneous or sequential recovery of the fruit juice and of the essential oil, by collecting the oil with a spray of water after the abrasion (scarification – puncture by pins) before or during the expression of the fruit juice.

    • Most facilities allow for the simultaneous or sequential recovery of the fruit juice and of the essential oil, by collecting the oil with a spray of water after the abrasion (scarification – puncture by pins) before or during the expression of the fruit juice.

    • Enzymatic treatment of the residual water allows recycling, and markedly increases the final yield of essential oil.

    • Citrus oils are also obtained directly from the fruit juices (by vacuum de-oiling)



    Steam distillation by microwaves under vacuum. In this procedure, the plant is heated selectively by microwave radiation in a chamber inside which the pressure is reduced sequentially.

    • Steam distillation by microwaves under vacuum. In this procedure, the plant is heated selectively by microwave radiation in a chamber inside which the pressure is reduced sequentially.

    • fresh plants require no added water.

    • ADVANTAGE: This method is fast, consumes little energy and yields a product which is most often of a higher quality than the traditional steam distillation product.



    • SOLVENT EXTRACTION

    • Extraction is generally preceded by a process of: bruising the fresh, wilted or semi-desiccated organs, chopping herbaceous drugs, pounding roots & rhizomes or turning wood into chips or shavings.

    • The procedure is conducted in specialized facilities e.g. Soxhlet-type extractor.



    The solvent selection is influenced by technical & economical factors

    • The solvent selection is influenced by technical & economical factors

    • - Selectivity (being a good solvent for the specific constituents).

    • - Stability (chemical inertness)

    • - Boiling point should not be so high that the solvent can be completely eliminated; nor too low, to limit losses & control cost

    • - Handling safety

    • Solvents most used are aliphatic HC’s – petroleum ether, hexane, propane & liquid butane.

    • Although benzene is a good solvent, its toxicity increasingly limits is use.



    At the end of the procedure, the solvent contained in the plant material is recovered by steam injection.

    • At the end of the procedure, the solvent contained in the plant material is recovered by steam injection.

    • Main disadvantages of solvent extraction

    • - Lack of selectivity, many lipophilic substances may end up in the concretes & render further purification necessary.

    • - The toxicity of solvents  leads to the restrictive regulations regarding their use

    • - Residues in the final product.



    These procedures take advantage of the liposolubility of the fragrant components of plants in fats.

    • These procedures take advantage of the liposolubility of the fragrant components of plants in fats.

    • a. “Enfleurage” – the plant material is placed in contact with the surface of the fat. Extraction is achieved by

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