The prized essential oil is located primarily in helichrysum’s flower petals, sepals, and bracts, with some oil also located along the stem leaves.

Thus, steam distillation is effective in extracting the essential oil, and remains the most common method used by commercial distillers.

Methods of Extraction

Steam Distillation

The most common method of obtaining helichrysum essential oil, regardless of the species, is by steam distilling the fresh flowering tops and occasionally, pieces of the stem. The plant material is loaded into a still and distilled for approximately two hours per ton using a ‘Clevenger-type’ apparatus. In the past, copper has primarily been used as the metal of choice; however, the ions in copper has been shown to affect the chemical constituents of the plant. For this reason, in recent years stainless steal has become the mainstay when distilling helichrysum.

Hydrosol

After obtaining all the essential oil possible from the helichrysum blossoms during steam distillation, the remaining water in the still is collected and used as a hydrosol. On occasion, the water that has been separated from the resulting essential oil is then reintroduced into the still. This process, called cohobation, allows for a more concentrated hydrosol as the water is re-infused with the plant material multiple times. Helichrysum hydrosols are reported to contain similar healing properties to their essential oil cousins, with perhaps a more subdued effect. Often, the hydrosol will be added to skin care blends in place of water in the recipe to impart a small amount of helichrysum’s benefits, adding a mild anti-inflammatory, anti-hematomol, and other skin regenerative effects.

Absolute via Solvent Extraction

Another method of obtaining the beneficial components from helichrysum is to solvent extract the precious oil from the flowers, creating Immortelle absolute, or Everlast. In solvent extraction, hexane tends to be the alcohol-based method of choice. However, when creating an organic, all-natural extract and thus similar extraction methods are desired, vegetable glycerin or sweet almond oil can be used as the solvent.

A two-step chemical process is typically employed to create the absolute. A simplified explanation of the process is described by Fakhry and Co.: “A conventional concrete is produced by solvent extraction using hexane; the absolute is displaced from the concrete using ethanol, and the by-product of concrete is wax.”

In the first stage, a concrete is created using a solvent such as hexane. The aroma emanating from the concrete will be different from that obtained by essential oil: aside from the remaining solvent odor, the concrete will impart an almost licorice-like fragrance to the usual herbaceous, floral, woody fragrance. Depending on the extraction solvent, the color of the absolute can range from olive green to almost brown. Regardless, almost all will have the waxy consistency typical of a concrete.

The second step of creating an absolute involves a second solvent extraction of the newly created concrete that results in the more refined absolute. Helichrysum absolute is a highly viscous (almost semi-solid), green or brown oil that has an odor similar to the waxy concrete but heavier in the floral, wood-like, herbaceousness with less of a residual waxy solvent.

The yield produced from absolute is often quite a bit higher than that of helichrysum essential oil. In addition, when the extraction of all the beneficial components of helichrysum is complete, the remaining spent plant material can be reused as a fertilizer for the next year’s crop, which has been asserted to increase yields of the subsequent harvest by up to 30%. 

However, higher yields do not translate into more medicinal benefits. Helichrusym absolute is typically lacking the high levels of di-ketones, neryl acetate, curcumenes, and other beneficial components often present. Thus, it is used more often for its tenacious fragrance in perfumery than as a medicinal oil. Another caveat when working with helichrysum absolute is that high amounts of tannins tend to be present in the final product. This can have an effect on the color produced when mixing helichrysum absolute with other oils that tend to have trace amounts of metals present, giving the resulting oil a dark, blackish hue. 

Supercritical Fluid Extraction

While not routinely employed as an extraction method to obtain essential oil due to the prohibitive cost, supercritical fluid extraction is a solvent-free method that uses pressurized carbon dioxide at lower temperatures than those used in steam distillation, thereby introducing less degradation of the volatile chemicals. However, supercritical fluid extraction can produce oils with sometimes drastically different chemical profiles and yields, as evidenced by a recent study conducted by Costa et al.