Refining essential oils Episode n°2 : Molecular distillation
The short-path distillation process (or molecular distillation) allows the purification of heat-sensitive, high-boiling point products, such as essential oils.
By Nicolas Tetard, Sales and Marketing Manager at Nature & Technologies
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Nature & Technologies, a specialist in solutions for processing natural products with high added value, offers extraction solutions but also for the valorization of products extracted from plants. One of the products commonly obtained in the field of natural products is crude essential oil. This is a variable mixture of different volatile compounds that sometimes need to be reworked.
In terms of refining crude essential oils, two solutions are generally considered:
1.Fractional distillation or rectification
2.Molecular distillation
In this second episode, we will focus on the molecular distillation process, also called short-path distillation.
The short-path distillation process (or molecular distillation) allows the purification of heat-sensitive, high-boiling point products, such as essential oils.
Principle :
The crude product is processed in a kind of thin-film evaporator under very high vacuum (up to 1.10-3 mbar absolute) and at high temperature. Only the lightest components vaporize. They condense almost immediately on the internal condenser installed in the center of the evaporator. Thus, the exposure of the distillate to high temperatures is minimal. This is due to the “instantaneous” vaporization of the distillate on the heated wall of the evaporator and the short distance between the evaporator and the condenser, where the fluids are in free molecular flow regime. At the end of the process, we get two fractions:
- One, called “residue”, which contains the heavy parts, the coloring, some pesticides, etc.
- One, called “distillate”, which contains the refined light parts
Equipment :
In terms of equipment, Nature & Technologies designs both pilot-sized units and industrial plants. For example, we offer evaporators made of stainless steel (and sometimes glass – for pilot application) with evaporation surfaces ranging from 0.06 m² to more than 9 m² – any intermediate surface being feasible. Nature & Technologies has equipped several major players with molecular distillation units of different capacities, in the fields of perfumes, aromas, cosmetics or more generally in the processing of natural raw materials with high added value. Our customers have chosen us for our ability to provide highly reliable, fully customized equipment that perfectly meets their needs.
Example :
Discoloration of citrus essential oils, including pesticide removal, is an example of the use of short-travel distillation.
Testing and development :
Each product is unique and requires a tailor-made solution to ensure a high-quality result. Through its collaborative testing and development platform, the WiNatLab, Nature & Technologies supports you in the development of your products by defining a finely tuned equipment adapted to the desired goal. Tests on molecular distillation pilot equipment are also possible.
To learn more, visit the WiNatLab page.