Essential oil extraction is a subject for study for aromatherapists. This is because, there are so many things involved in extraction of oils from plant parts like roots, flowers, bark, resin, rinds and fruits etc. However, there are several extraction methods which are used to extract essences from plants. These methods are often known only to aromatherapists and aromatherapy students and are often practiced on a small scale. The most popular of the methods is steam distillation. This has been prevalent from the eighth century and practiced by the Arabs, Egyptians and others. Distillation is used only for extraction of oils from leaves, barks, seeds, stems and roots. There are several less known methods of extraction too. They are Expression, Enfleurage, Maceration and Solvent Extraction.
Extraction nuances: Essential oils extraction is not easy as any other industrial processes. Since we deal with delicate raw materials like plant products, it involves nuances of a subtle kind. The percentage of raw materials is to the end result varies depending on type of plant used. The method of extraction and the quality of plant used determines the oil’s value and price. For instance, it takes 12,000 Rose petals to produce 5 ml of Rose essential oil, while 100 kilos of Lavender to produce 3 liters of Lavender oil. As a result, Rose is about 20 times costlier than Lavender in the market. Similarly, raw materials vary from plant to plant, oil to oil. Lavender is extracted from its flower, Orange/citrus fruits from their rinds, Frankincense from the resin of its tree, Cinnamon is taken from its bark while Pine is extracted from its needles. Soil quality, climatic conditions and harvest time/distillation/extraction process of a plant determine an oil’s purity. There are other nuances like – Jasmine flowers must be picked by hand at dawn (if they are for extraction) and Sandalwood must be 30 years old and at least 30 feet high to produce best quality oil.
Essential oils extraction methods: Below is a brief of essential oils extraction methods like Expression, Enfleurage, Maceration and Solvent Extraction.
1. Expression: Most of the citrus fruits like Orange, Lemon, Mandarin, Bergamot and Lime are extracted from this method. This is a simple method which squeezes the rind of fruits to produce essences.
2. Enfleurage: This method uses a fixed oil, mostly a vegetable oil or animal fat or lard. It involves use of a sheet of glass mounted on a wooden frame. The plant part from which the oil is to be extracted (flower petals) should be placed on the sheet, mixed with fixed oil. Then, the whole sheet is placed in the sunlight. Later, this mixture is dissolved in alcohol and evaporated from it during the final process. Rose, Neroli, Jasmine and Violet are usually extracted from this method. Labeled ‘absolute’, enfleurage is quite rare as it is very expensive.
3. Maceration: Maceration is just like Enfleurage which uses a heated up fixed oil to release the essential oil from the plant parts easily.
4. Solvent Extraction: This is a process in which essential oils is extracted from delicate flowers like Rose, Jasmine, Violet or Mimosa. Here, a solvent like petroleum ether is used to extract essential oils which is later dissolved in alcohol. The procedure is like this: flower petals are placed on metal perforated trays. The extracts are called absolutes and are expensive than enfleurage.