Move your mouse along labels to explain their purpose.
Move your mouse along labels to explain their purpose.
Steam is required to extract essential oils as they are only slightly soluble in cold water.
Grid: This is designed to hold the plant material and allow the stem to circulate through it.
The plant material is cut up to into small pieces. The essential oils from the material dissolves in the steam which is under pressure and above 1000C. This process takes place quickly to minimise damage to the oils due to heat.
Steam and oil leave the plant material as a vapour.
Water has a cooling effect on the vapour containing the essential oil.
In the cooling coil the vapour cools and returns to a liquid (condenses).
When the liquids (distillate) reach the collecting vessel the essential oil, which is only slightly soluble in water, floats on top of the water and can be drawn off. Since the water phase contains a small amount of essential oil it is often retained and marketed as a floral water.
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| Belfast Institute of Further and Higher Education | ||||||||||||||||||
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Steam Distillation The plant material is placed in a still and steam under pressure is passed through it from the bottom. This causes the essential oil to vapourise and it is carried with the steam into a condenser. This cools the mixture and the steam and essential oil return to their liquid phase. Since the two liquids are virtually immiscible, when they pass into a final collecting vessel the oil will float on the water. It can then simply be decanted off. The remaining water is often marketed by the perfumery industry as a perfumed water. |
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