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



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Cold diffusion into the fat

  • Digestion – carried out with heat, by immersing the plant in melted fat (also known as hot enfleurage).

  • The final product is known as a floral pomade.



  • b. PNEUMATIC METHOD: similar in principle to the enfleurage process.

    • b. PNEUMATIC METHOD: similar in principle to the enfleurage process.

    • It involves the passage of a current of hot air through the flowers.

    • The air, laden with suspended (extracted) volatile oil, is then passed through a spray of melted fat in which the volatile oil is absorbed.



    Beyond its critical point, a fluid can have the density of a liquid & the viscosity of a gas  therefore diffuses well through solids, resulting in a good solvent.

    • Beyond its critical point, a fluid can have the density of a liquid & the viscosity of a gas  therefore diffuses well through solids, resulting in a good solvent.

    • CO2 is the main gas used

    • Advantages of CO2

    • - It is a natural product

    • - chemically inert, non-flammable

    • - non-toxic

    • - easy to completely eliminate

    • - selective

    • - readily available

    • - Inexpensive



    DISADVANTAGE: Technical constraints

    • DISADVANTAGE: Technical constraints

    • - High cost of initial investment

    • ADVANTAGES:

    • - obtain extracts which are very close in composition to the natural product.

    • - It is possible to adjust the selectivity & viscosity, etc by fine tuning the temperature & pressure

    • - All result in the increase of popularity of this type of method



    • USES

    • Initially developed to decaffeinate coffees, prepare hops extracts or to remove nicotine from tobacco, the method is now used to

    • - Prepare spice extracts (ginger, paprika, celery)

    • - Specific flavours (black tea, oak wood smoke)

    • - Plant oils

    • - To produce specified types of a certain product, e.g. thujoneless wormwood oil.



    Occasionally it is necessary to decolourize, neutralize or rectify the oils obtained.

    • Occasionally it is necessary to decolourize, neutralize or rectify the oils obtained.

    • Steam jet under vacuum

    • Allows for the elimination of smelly or irritating products, and to obtain a final product of desired “profile”.

    • Chromatrographic techniques

    • This permits a good separation of the essential oil from non-volatile lipophilic compounds.



    Occurrence of Chemotypes

    • Occurrence of Chemotypes

    • Influence of the vegetative cycle

    • Influence of environmental factors

    • Influence of preparation method



    Chemical breeds commonly occur in plants containing volatile oils, e.g. Thyme (Thymus vulgaris) – has 7 different chemotypes, each with slightly different types & amounts of volatile oils.

    • Chemical breeds commonly occur in plants containing volatile oils, e.g. Thyme (Thymus vulgaris) – has 7 different chemotypes, each with slightly different types & amounts of volatile oils.



    Proportions of the different constituents of a volatile oil may vary greatly throughout its development. Wide ranges are commonly found in fennel, carrot and coriander (linalool is higher in ripe fruit than unripe fruit). Mentha (peppermint) is also greatly affected by the vegetative cycle.

    • Proportions of the different constituents of a volatile oil may vary greatly throughout its development. Wide ranges are commonly found in fennel, carrot and coriander (linalool is higher in ripe fruit than unripe fruit). Mentha (peppermint) is also greatly affected by the vegetative cycle.



    Temperature, humidity, duration of daylight (radiation), and wind patterns all have a direct influence on volatile oil content, especially in those herbs that have superficial histological storage structures (e.g. glandular trichomes). When the localization is deeper, the oil quality is more constant.

    • Temperature, humidity, duration of daylight (radiation), and wind patterns all have a direct influence on volatile oil content, especially in those herbs that have superficial histological storage structures (e.g. glandular trichomes). When the localization is deeper, the oil quality is more constant.



    e.g. Peppermint: long days & temperate nights  higher yields of oil & menthofuran. Cold nights lead to an increase in menthol.

    • e.g. Peppermint: long days & temperate nights  higher yields of oil & menthofuran. Cold nights lead to an increase in menthol.

    • Laurus nobilis (Bay) [volatile oil] is greater in the southern hemisphere than the northern.

    • Citrus: higher temperatures = higher oil content.



    Cultivation practices also play an important factor to the yield & quality of the final product.

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