The most appropriate production process of essential oil production from the leaves of eucalyptus globulus plant is steam distillation.
Generally speaking steam distillation is the most common method of extracting essential oils. First, fresh or sometimes dried, botanical material is placed in the plant chamber of the still and pressurized steam is generated in a separate chamber and circulated through the plant material. The heat of the steam forces the tiny intercellular pockets that hold the essential oils to open and release them. The temperature of the steam must be high enough to open the pouches, yet not so high that it destroys the plants or burns the essential oils. As they are released, the tiny droplets of essential oil evaporate and, together with the steam molecules, travel through a tube into the still's condensation chamber. As the steam cools, it condenses into water. The essential oil forms a film on the surface of the water. To separate the essential oil from the water, the film is then decanted or skimmed off the top. The remaining water, a byproduct of distillation, is called floral water, distillate, or hydrosol.
There are alternative ways of producing essential oils. These are Cold Pressing or Cold Compression (which is mainly used to obtain citrus fruit oils), and Solvent Extraction (a method of extraction used on delicate plants). However, for the eucalyptus globulus, steam distillation is more appropriate.