Steam Distillation

Steam distillation is a method employed to extract the aromatic components contained within raw plant materials, utilizing the heat generated by boiling steam. In this process, both water and the plant material are heated simultaneously. As the steam cools, the essential oil and water separates into two distinct layers due to differences in solubility and specific gravity. The water portion is utilized as aromatic distilled water, often referred to as floral water or herbal water, as it contains a smaller amount of aromatic components

The boiling point of aromatic components is typically higher than that of water. However, when they are heated alongside water, they can transition into a gaseous state at a lower temperature than their individual boiling points (approximately equivalent to the boiling point of water).

Example: Steam distillation of essential oil component A (boiling point at 200℃)

At 98°C, both water and essential oil component A exhibit vapor pressures that are slightly lower than atmospheric pressure, indicating that neither of them has yet reached its respective boiling point.

In the distillation process of essential oil component A, when the total vapor pressure of water and component A reaches atmospheric pressure at 98°C, both water and component A will come to a boil and transform into gas.

Essential oil component A can be extracted at a temperature lower than its original boiling point. However, it’s essential to note that the process typically involves heating to about 100°C, and this heat can affect components whose aroma or composition is sensitive to temperature changes.

Here are some known steam distillation methods, each utilizing distinct techniques:

Water Steam Distillation

A method that involves placing a mesh at the base of the distillation vessel, situating plant material above the mesh, and positioning water below the mesh. The water is then heated, creating steam that passes through the plant material. It is commonly used in both industrial and household settings.

Steam Distillation

A distillation method which steam is generated separately from the distillation kettle, and the heated steam is then introduced into the distillation kettle containing the plant material for the extraction process. It is primarily employed for industrial purposes.

Water distillation（Boiling distillation）

A distillation method in which plant materials are completely immersed in water and then heated. This method is particularly effective for efficiently extracting aroma compounds from materials such as wood and fruit peels, as well as other materials that internally contain aromatic components.

・Cohobation (redistillation)

A distillation method which distilled water, obtained once, is distilled again to obtain a compound ccloser to the actual composition.

Vacuum Distillation

A distillation method in which a vacuum is created in a water steam distillation facility to lower the boiling point. This method is used to extract aroma components that are difficult to extract at high temperatures.

References: Jennie Harding [Handbook of Essential Oil and Plant Oil] Tokyo-do Publishing, 2010.; Shinichiro Otsuki/Yukiko Ozaki [Scientific Name Etymology Dictionary of Herbs] Tokyo-do Publishing, 2009.; Jennie Harding [Illustrated Reference Book of Herbs] Sancho Publishing, 2012.; Freddy Ghozland/Xavier Fernandez [L’Herbier Parfume] Hara Publishing, 2013.; Kyohei Mikami [Comprehensive Guide to Essential Oils] Fragrance Journal, 2010.; Yuzuru Ogura [Dictionary of Plants] Tokyo-do Publishing, 1957.; Nobuo Ohashi [Dictionary of Medical Herbs] Tokyo-do Publishing, 2016.; Wanda Sellar [The directory of essential oils] Fragrance Journal, 1992.; Aroma Environment Association of Japan [AEAJ Aromatherapy Certification Official Textbook grade1&2] Sekaibunka, 1999.; Water steam distillation
http://apotheca.jugem.jp/?eid=2
http://gakuin.org/q/backnumber/2015/15/15.html
https://sara-green.info/contents_390.html; Vacuum distillation
https://www.seika.com/product/aroma/

Supervisor: Yamamoto Perfumery co., ltd.

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