Being familiar with the extraction processes for oils can be critical knowledge when offering holistic skin care treatments. The following techniques are some of the most commonly used.
Tinctures—Alcohol or glycerine is used to extract fat-soluble compounds from the plant material. Tinctures contain tannins, polyphenols and flavonoids specific to the botanical identified in the extraction. Also, tinctures produced for the medicinal market are best for their guaranteed potency.
Aqueous extracts—Water extractions, such as tea, are referred to as aqueous extracts, infusions or decoctions. Infusions contain water-soluble compounds, though lower temperatures will also extract some fat-soluble properties, such as the polyphenols in green tea. The amount of therapeutic compounds will be dependent on the process and heat used, as well as the skill and integrity of the producer.
Expeller-pressed—The mechanical method used to get expeller-pressed fixed oils from nuts, seeds and algae uses a screw press machine. These may still go through an RBD process once extracted. Fixed oils contain saturated, mono- and polyunsaturated fatty acids. The unrefined oils retain vitamins, chlorophyll and some polyphenols, flavonoids and carotenoids.
Solvent extracts—Fixed oils are also extracted using hexane or other solvents. Solvents may contain contaminants that remain in the oil. Hexane is used to produce absolutes, such as jasmine, rose or tuberose, due to the essence being very fragile in these plants and distillation being too difficult to achieve.
Distillation—Water, water/steam or steam distillation is used to extract volatile compounds such as essential oils. Water/steam or water are most effective in retaining the highest amount of therapeutic composition that includes mono-, sesqui- and diterpenoids, and trace elements, and essential oil quality is highly dependent on the skill of the distiller.
Supercritical carbon dioxide, or CO2—This modern method of extraction places plant material in a high-pressure container with carbon dioxide in a supercritical state. This is an extremely effective method of capturing intensely concentrated therapeutic compounds. CO2 extracts are used in aromatherapy and as medicinal supplements. Color in skin preparations should be evident due to concentrated carotenoid and flavonoid content.
Isolates—Isolates are compounds isolated from a plant source, such as vitamin E, allantoin or resveratrol. Many isolates are synthetically created, such as dl-tocopherol acetate (vitamin E), ascorbic acid (vitamin C), niacin (vitamin B3) or alpha lipoic acid. Though isolates are a step away from the whole food concept, they provide a support, or increased activity, to a treatment or formula. Isolates can be used to increase or expand on properties that include antioxidants, anti-inflammatories or activities specific to the isolate used.