Aurudistillatsioon

Aurudistillatsioon, also known as steam distillation, is a separation technique that exploits the volatility differences of compounds in a liquid mixture. In this process the mixture is heated to produce vapors, which carry volatile components out of the mixture. The vapors are then condensed into a liquid condensate that contains the distilled material while most of the nonvolatile substances remain in the residue.

The technique was first developed in the early 19th century for the extraction of essential oils from plant material. Charcoal and glass vessels were used initially, but the invention of the Parr vessel in the 1930s allowed the production of higher pressure vapors, increasing yields and efficiency. Steam distillation has since become a standard procedure in the oil, flavor, and fragrance industries.

During aurudistillatsioon, the feed material is placed in a heating vessel. Steam is introduced and the mixture reaches its boiling point, often below the normal boiling point of the feed material. Volatile compounds evaporate with the steam; the combined vapors move to a condenser where they cool and recondense. The condensate is typically a two-phase mixture consisting of an essential oil layer atop an aqueous layer, which are then separated by decanting or centrifugation. The nonvolatile residue is left behind in the distillation column.

Common uses include the extraction of citrus oils, linalool, and other terpenoids. It is also employed in the pharmaceutical sector for the isolation of certain alkaloids and glycosides. Because the operating temperatures are lower than direct boiling, heat‑labile compounds can be preserved more effectively.

Limitations of the method include the need for a large amount of water and relatively long processing times. Moreover, not all compounds are sufficiently volatile, making the distillation of high-molecular-weight substances impractical. Despite these drawbacks, steam distillation remains one of the most widely adopted methods for extracting aromatic and essential compounds.