Essential oil in the making…

An essential oil is a wonderful product, but how is it extracted? There are various ways of doing this. We’d love to tell you more about it in this in-depth blog post.

Essential oil – what is it?

An essential oil is a mixture of volatile, aromatic compounds extracted from plant material, which are characteristic of the scent of the plant or fruit from which they are extracted. You’ll probably recognise this: you peel an orange and there are lots of tiny droplets on the table. This is the oil that has been released by the pressure on the peel. Although it is called ‘oil’, essential oils contain no fat at all.

Essential oils are extracted in various ways from different parts of a plant. For example, oil is extracted from the blossoms, fruits, seeds, leaves, fruit peel, bark or wood. The method used to extract an oil depends on the plant material. For example, you can press oil from the peel of an orange, whereas you cannot press oil from a piece of bark. Some types of essential oil are quite expensive. This is because it sometimes takes a large number of plants to produce a small amount of oil. For example, to produce the expensive rose oil, 6,000 kilos of rose petals are needed to yield 1 kilo Rose oil to produce. Citrus oils are a lot cheaper. For example, for a Orange oil 200 kg of ripe husks are needed to produce 1 litre of oil. That is why there can be such a wide variation in the price of a single-variety oil. The method used to extract the oil can also affect the price.

Extraction of an essential oil

Essential oils are therefore extracted in various ways. The most common method of extraction is steam distillation.

The diagram above shows a still used to distil oil using steam. In this process, steam is passed through the plant parts to be processed by means of heat. The essential oil evaporates with the steam and moves to the section where the steam is cooled and collected. Once the steam has cooled to water, the essential oil can be separated from it due to the difference in polarity between the oil and the water. The water that remains – the by-product – is called hydrolat. This contains a hint of the essential oil’s scent and is lovely to use, for example, as a facial spray to refresh your skin.

Cold pressing

One method used, for example, with citrus fruits is cold pressing. In this process, the oil-rich peel of the fruit is mechanically pressed. This ensures that the fresh aromas of the citrus fruits are well preserved. This method of pressing is carried out without any chemical additives and at a temperature not exceeding 35°C.

Dry distillation

This method is used for certain types of wood. It involves gently heating the solid material, causing the essential oil to evaporate. The water vapour is then condensed.

Extraction

Carbon dioxide (CO₂) extraction is a modern technique for collecting essential oils by using CO₂ as a solvent. Although the equipment required for this method is expensive, the overall process is quick and efficient compared with steam distillation. It also yields relatively high-quality essential oils.

Enfleurage

There are two methods of enfleurage:

𝙺𝚘𝚞𝚍𝚎 𝚎𝚗𝚏𝚕𝚎𝚞𝚛𝚊𝚐𝚎 – In this process, the flowers from which the scent is extracted are placed on trays that have been coated with a thin layer of animal fat (usually lard or beef tallow, in any case odourless). The trays are placed close together on a rack. The flowers are regularly replaced with a fresh batch. The scent of the flowers is absorbed into the fat. Over time, the fat becomes sufficiently saturated.

𝚆𝚊𝚛𝚖𝚎 𝚎𝚗𝚏𝚕𝚎𝚞𝚛𝚊𝚐𝚎 – In this process, the flowers are placed in melted fat. As with cold enfleurage, the flowers are replaced regularly.

The fat therefore absorbs the oil from the plant material and, over time, develops a wonderful scent. This scented fat is also known as a pomade. An absolute can be made from this by steeping the pomade in alcohol. The alcohol does absorb (some of) the aromatic compounds, but absorbs the fatty substances not at all, or only to a very limited extent. Once the alcohol has evaporated, the absolute remains. An absolute is an extract produced using specific solvents, such as hexane or alcohol. These solvents are removed from the extract as thoroughly as possible, though a residual alcohol content of up to 2% is certainly possible. Nowadays, the costly enfleurage technique is often replaced by solvent extraction. The Jasmine oil is an example of extraction using the enfleurage method.

𝙻𝚒𝚎𝚏𝚜 𝚁𝚎𝚋𝚎𝚌𝚌𝚊