technical terminology also essential oils are soluble in organic solvents extracts or the organic phase of water vapor distillates from plants or plant parts, which have a strong characteristic of the origin plant odor. Essential oils are composed of many different components, but they do not contain fats. In addition to essential oils Hydrosols exist as byproducts of steam distillation. They contain the water-soluble components of the distilled plants and traces also ethereal oils.
Extraction of oils
The most common method for the recovery of essential oils is steam distillation. For this is blown into a sealed combustion boiler with shredded plant material hot steam. The steam drives the essential oil from the plant. Into a chilled tube condenses the oil-water mixture, and in a receiver, the essential oil is separated from water. Some plants, which can not be distilled alone, such. As algae, nettle or hay can be distilled by co-distillation with another plant as a carrier. Oils of some kinds of flowers such as jasmine, tuberose or mimosa, can not be obtained by steam distillation.
The cold pressing is only used for citrus oils. The shells are pressed so that an emulsion of liquid and essential oil is produced. The oil is separated by centrifugation.
Extraction is practiced mainly at flower oils. For this, the plants are placed in a solvent, usually placed hexane which removes all the soluble flavorings, also waxes and dyes. The solvent is then distilled off. What remains is a waxy material that is extracted or distilled again with alcohol. Such essential oils are also called absolutes. A residue control can ensure that no solvent is in the essential oil. The very costly extraction with fats, the so-called cold absorption is practiced hardly today.