How to Extract Citrus Oils

There are two main ways of extracting oils: expression (Cold Pressing) and Distilation.

Cold Pressing

An old, simple method of extracting oil through cold pressing or expression, involves:

1. Soak citrus rind in warm water to soften.
2. A sponge is pressed into the softened rind; soaking up oils and moisture into the cavities of the sponge.
3. The sponge is then squeezed over a container (e.g. bucket) to produce a mixture of oil, water and juice.
4. Leave until a layer of oil separates out then siphon the oil off.

This technique has been used traditionally to produce oils from tangerine, lemon, lime and orange.

A more modern technique of cold pressing involves using a purpose built machine that punctures the rind to release oils as it is spun inside a container (type of centrifuge). The spinning at the same time will separate the oil from the citrus juice.

Distillation

Distillation involves placing plant material inside a container that can be heated (a still). There is one outlet at the top of the container, which connects via a pipe to a second collection container. When the contents of the first container heats, the oils will vaporize and that vapour rises, moving into the pipe and travelling to the seconds container. As it moves along the pipe, the vapour cools and oil goes from gas to liquid. Any water that moves along the pipe will separate out from oil in the second container (Oil will form a layer on top of water; from where it can be siphoned off).

There are three types of distillation

1. Water distillation involves mixing the plant material with water then heating the solution. This is used with citrus flowers; but the flowers can stick into clumps making full extraction of oils more difficult.
2. Water and steam distillation involves suspending the plant material on a grate above boiling water in the still. Steam rises through the vegetation capturing oils as it moves up. This is more often used with distillation of foliage.
3. Steam distillation involves creating steam outside of a compartment (still) containing the plant material, then injecting that steam into the compartment under a slightly higher pressure. Pressurised steam then captures the oils and rises to exit through the top outlet.
   
   

Distilled oils tend to have different characteristics to expressed oils. Distilled citrus oils are generally considered a lower quality; though distilled lime oil is considered a higher quality than expressed lime oil.

This is an extract from our citrus e book; available to purchase on this web site.