How is tea tree essential oil obtained?

The Tea tree, also known as tea tree plant or alternatively leafed melaleuca, is a shrub native to New Caledonia and Madagascar, but the leading producer today is Australia.

The leaves of the tea-tree were introduced to Europe by the English navigator James Cook, who discovered them in the islands of the New Zealand archipelago during his voyage. The aborigines used them to make a refreshing drink they called tea. Thus, in the absence of real tea, James Cook's crew came to appreciate infusions made from tea-tree leaves.

Furthermore, they also observed that the natives used this plant, specifically the leaves, to create poultices and treat infections. However, it was not until 1922 that the antiseptic properties and antibacterial properties of the plant were demonstrated by the chemist Arthur DE RAMAN PENFOLD. At the start of the Second World War, theessential oil of tea tree was added to every first aid kit of thearmy and the Australian navy due to its anti-infectious virtues.

It is important to note that the tea tree and the tea plant are often confused: the tea plant belongs to the Theaceae family and originates from Asia, while the tea tree is part of the Myrtaceae family and is native to Australia.

The tea tree essential oil is the result of a steam distillation (hydrodistillation) process.The setup consists of a distillation flask/reservoir, a condenser, and a thermometer.

1. The sample for extraction is prepared by cutting the leaves and young branches into small pieces.

2. The plant material is then added to a flask and immersed in several litres of distilled water.

3. Then, the setup is sealed to make it airtight and the process is initiated at a temperature of 250°C. The procedure then lasts for 4 to 5 hours.

4. The oil is collected in a separating funnel and then it is stored in a cool and dry place.

The percentage of the extracted oil is calculated using the following formula:

Essential oil yield % = Volume of extracted oil/Fresh weight of plant material (g) × 100.

Upon application of this formula, the yield is as follows: 100 kg of tea tree leaves were required to harvest 1 to 2 litres oftea tree essential oil. Organoleptically, it is a clear, colourless to pale yellow liquid with a woody scent. It primarily containsmonoterpenols(approximately 45% terpinen-4-ol) andmonoterpenes(gamma-terpinene, alpha-terpinene, limonene). These compounds are responsible for itspurifying and sanitising properties.