ABSTRACT
Essential oils are aromatic, volatile liquids derived from plant materials such as leaves, fruit, bark, roots, wood, heartwood, gum, balsam, berries, seeds, flowers, twigs, and buds. Plants secrete essential oils in their specialized cells or glands to protect themselves from predators and pests and to attract pollinators. Essential oils are products or mixtures of fragrant or odorless substances. They are often named after the plant from which they originated. About 3000 essential oils are isolated from at least 2000 plant species, 300 of which are commercially important. High-quality essential oils are extracted from plant materials using standard extraction techniques such as steam distillation, water distillation, solvent extraction, cold press extraction, maceration, and enfleurage. The extracted essential oils exist as mixtures with the solvent of extraction. Therefore, the solvent should be separated using different techniques. For instance, anhydrous sodium sulfate removes water molecules from the essential oils after steam or water distillation. If not properly stored, essential oil composition can also change during storage after distillation, mainly due to environmental factors such as light incidence, atmospheric oxygen, and temperature. The pure essential oils, from which the solvents are removed, should therefore be stored in dark glass bottles or containers with tight-fitting lids in a cool, dark place, away from sunlight.
