How Essential Oils Are Made

Expression / Cold Pressing
Another popular extraction method is through pressing. This method was named appropriately - the oil is basically pressed or squeezed out of the fruit or plant. This also used to be the method used in the middle ages to extract the essential oils, and used to be done by hand, which was painstakingly slow, but yielded a very high-quality oil.

The process is simple-sounding. Pockets of the desired oil are contained within the peel of a fruit. You can see this first-hand by taking the peel of almost any citrus fruit (lemons, oranges, grapefruits, etc...) and squeezing it to see the resulting spray of oil, caused by the pockets of oil breaking under the pressure. When this was done by hand, a sponge was used to collect that spray, and the oil was squeezed from the sponge and filtered to produce a clean product.

Nowadays, this whole process is automated. The fruit is pierced multiple times with tiny, sharp points that break the oil pockets. The fruit itself is then squeezed by a machine, which mixes the fruit juice with the oil. The juice and the oil are then separated by a centrifuge, and the oil is collected. The resulting oil is then named an "expressed" oil.

One advantage of pressing is that the oil is never submitted to high temperatures, and thus does not lose any flavor. So expressed oils can also be used as flavoring components.

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