Höyrytislaus

Höyrytislaus, or steam distillation, is a method used to extract volatile compounds, especially essential oils, from plant material by passing steam through the material. The steam lowers the boiling temperatures of the aromas, enabling distillation at temperatures lower than direct heating and helping to preserve delicate constituents.

The term Höyrytislaus comes from Finnish, with höyry meaning steam and tislaus meaning distillation. The method is widely used in the essential oil and perfume industries, as well as in laboratories and traditional plant processing.

Principle: Plant material is placed in a distillation vessel and exposed to steam generated in a boiler or steam generator. The steam carries volatile compounds into a condenser where they condense into a two-phase distillate: an essential oil layer and a hydrosol (water phase). The oil is separated from the water and collected.

Equipment and variants: Common setups include a steam generator, a distillation pot, a condenser, and a receiver. Variants include atmospheric steam distillation and dry steam distillation; there can be single-stage or multi-stage configurations. Temperature typically correlates with steam pressure and is often below temperatures needed for direct boiling of plant material.

Applications and considerations: Steam distillation is favored for heat-sensitive materials because it minimizes thermal degradation and hydrolysis. It is widely used for essential oil production, herbal extracts, and perfumery. Limitations include potential co-distillation of unwanted compounds, the need for careful process control, and the separation of oil and hydrosol. Equipment requires attention to corrosion, scaling, and maintenance.

See also: steam distillation, essential oil, hydrosol, plant extraction.