Dampfdestillation

Dampfdestillation, also known as steam distillation, is a separation and extraction method used to recover volatile constituents, especially essential oils, from plant materials. It relies on volatile components co-distilling with water steam at temperatures below the boiling points of the compounds, allowing sensitive constituents to be captured without thermal degradation. In a steam distillation setup, steam generated in a boiler passes through plant matter held in a distillation chamber. The steam volatilizes the oil and other volatile substances, and the vapor is carried to a condenser where it cools and forms a mixture of essential oil and water (hydrosol). Because most essential oils are immiscible with water, they separate as an oil layer that can be separated from the water layer.

Dampfdestillation is distinguished from hydrodistillation, in which plant material is immersed directly in boiling water; in steam distillation the plant material is contacted by steam rather than submerged. The technique is widely used for extracting essential oils from herbs and spices such as lavender, peppermint, rosemary, and citrus peels, and it is compatible with thermally sensitive components. Advantages include operation at relatively mild temperatures and suitability for heat-labile compounds; drawbacks include potential hydrolysis or formation of emulsions and generally lower selectivity for mixtures with many nonvolatile components.