Essential oils are the natural aromatic compounds found in seeds, bark, stems, roots, flowers, and other parts of plants. They are non water-based phytochemicals made up of volatile organic compounds. They give plants their distinctive smell and also provide plants with protection against predators and disease and also play a role in plant pollination. They are fat soluble, but do not include fatty lipids or acids found in vegetable and animal oils. Pure, unadulterated essential oils are translucent, range in color from crystal clear to deep blue, and when applied to the skin are immediately absorbed. They have been used throughout history in many cultures for their medicinal and therapeutic benefits.
Essential oils are most often retrieved via low-heat steam distillation. Steam is circulated through the plant material under pressure so that the oils separate from the plant and combine with the steam. As the steam mixture cools, the water and the oil naturally separate and the oil is collected. Temperature and pressure must be closely monitored to ensure highest quality oil extract of the correct chemical composition. This is a complex process, if too little heat is used it will not release the oil, and if too much heat is used it can change the composition and potency of the oil.
Along with the complex extraction process is the careful selection of the correct plants and plant parts harvested at the right time. It is as much an art form as it is science, and requires experienced growers and distillers working together to ensure a high quality product.
Steam distillation is the most common form of extraction, but oils such as citrus are extracted through compression. In this process the oil is squeezed from the plant. Also very few essential oils are extracted using solvents that bind with the oils and are later removed from the final product.