One of the reasons for our love affair with personal care and home fragrance products is our abiding attraction toward scents. Whenever possible, we use naturally extracted scents for their authenticity, allure, and complexity. For scents that don’t lend themselves to natural extraction due to the fragility of the fragrance components and/or the prohibitive costs, we use phthalate-free fragrance oils. Our lotions, lip balms, facial products, and deodorants (i.e. any product that stays on the skin) are naturally scented, and we refer to the scent components in their ingredients list variously as essential oils, absolutes, resins, distillates, etc.
In this jot we aim to explain what these terms mean and how natural scents are derived. The terms are typically associated with the method of extraction of the scent components.
Essential oils are scent extracts derived from plants by distillation or by mechanical pressing. Distillation entails heating the plant material to vaporize the volatile fragrant components then cooling the vapor to collect them as a liquid or a solid distillate. For example, lavender essential oil is obtained by steam distillation in which steam is injected into a vessel containing lavender buds. The steam heats up and breaks down the plant material, and carries with it the volatile fragrant oils in the plant. The mixture of steam and oils is then condensed back into a liquid and separated. The oil thus obtained is lavender essential oil. The water phase contains water-soluble fragrant components of lavender and is dubbed lavender distillate or hydrosol, or more colloquially as “lavender water”. We use this hydrosol in our facial mists.
Oils obtained by mechanical pressing (also known as cold pressing or expression) include citrus essential oils. The peel of the citrus fruit or sometimes the entire fruit is pressed to rupture the oil-containing cells and release the essential oils. If entire fruits are used, the mixture is then centrifuged to separate the oil from the aqueous phase. Orange, grapefruit, lemon, tangerine, mandarin, and other citrus essential oils are obtained by this method.
The fragrant components of certain plants are too delicate for steam distillation and too scarce for mechanical pressing. Solvents such as volatile hydrocarbons (e.g. alcohol and hexane), solid oil or fat, or supercritical carbon dioxide (which is a liquid) are then used to extract the oils in a gentle fashion. For example, to obtain jasmine absolute, fresh jasmine blossoms collected early in the morning are laid onto thin substrates coated with a solid oil/fat. Over 1-2 days, the fragrant components from the flowers are transferred to the oils. The old blossoms are then replaced with fresh-picked ones until the solid oil is saturated. This solid product is known as the concrete (or pomade) and contains non-fragrant wax and other plant material in addition to the fragrant components. A volatile solvent such as alcohol or hexane is then used to extract the fragrant oils from the concrete. After the volatile solvent is evaporated off, the resulting product is known as the absolute. Absolutes tend to be richer and more concentrated and complex than essential oils derived by distillation or cold processing; their cost is commensurately higher.
Resins, such as benzoin and frankincense resins, are extruded from trees by slashing the bark and collecting the sap. These resins are often very thick and difficult to work with and are sometimes converted to essential oils by steam distillation or to a more fluid resin by solvent extraction.
Through the above extraction methods, we are able to experience a portion of the bounty of scents from nature even when we are not within smelling distance of the actual plant. In this way we have discovered the scents of plants in lands we have not yet seen. If you have a favorite essential oil, absolute or resin, we would love to hear more about it. We always relish a new olfactory treat.