Basics of Essential Oils

How Essential Oils Are Obtained

• Steam distillation: In this most common form of extraction, pressurized steam is added to plant matter, and the oil the plant produces is compacted, collected, and separated from the water. Steam distillation also produces hydrosol, or floral water, which is good for sensitive skin. Most leaves, twigs, and herbs—eucalyptus, lavender, fir, rosemary, thyme, dill, and others—are steam-distilled.
• Cold pressing: The inner skin of a citrus fruit, such as bergamot, orange, lemon, lime, or grapefruit, is pressed to release its oil. Cold-pressed oils tend to have a shorter shelf life than oils extracted by other methods.
• CO2: In this method, carbon dioxide is chilled to 35–55°F, pumped through the plant material, and condensed into a liquid. After pressure is released, the carbon dioxide escapes in gaseous form, leaving the essential oil of the plant behind. Oils that are extracted via this method have a richer, more intense scent, especially frankincense and chamomile.
• Solvent extraction: Delicate flowers such as jasmine, tuberose, and linden blossom are washed repeatedly with a solvent (such as hexane, petroleum ether, or methanol), yielding a waxy mass called a concrete. The wax is removed with ethanol, and the remaining substance is cold-filtered to produce the highly concentrated final product, called an absolute.

Shelf Life

• Citrus essential oils: Six months
• Other essential oils: About two years
• Hydrosols (floral waters): Shorter than their corresponding essential oils

Quality

Cost