Essential oils are volatile compounds that contain the aromatic essence of plants and flowers. Their extraction is a key process in sectors such as cosmetics, food and pharmaceuticals. Various technologies are available for obtaining them, depending on the type of raw material and the properties that need to be preserved.
Over time, different techniques have been developed to extract essential oils, ranging from artisanal methods to high-precision technologies. In this article, we explore two very different approaches: the enfleurage method, one of the oldest and most delicate techniques, and supercritical CO? extraction, a modern, safe and highly efficient alternative.
What is enfleurage method? Essential oil extraction
The enfleurage method is an extraction technique that uses an odorless fat to capture the volatile aromatic compounds found in flowers. There are two variations: cold enfleurage and hot enfleurage, with the cold version being the most widely known.
The process involves spreading a layer of fat onto flat glass trays (chassis) and covering it with fresh flower petals. These petals are periodically replaced until the fat becomes saturated with aromatic compounds. The saturated fat is then treated with ethanol to extract the absorbed aromas. Once the alcohol is evaporated, the final product, an absolute with high aromatic concentration, is obtained.
Innovative alternatives to the traditional extraction of essential oils
Compared to the enfleurage method, there are more suitable processes for industrial applications that demand high standards of quality, reproducibility and safety. The most commonly used techniques include:
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Steam distillation: involves applying steam to plant material to volatilize the essential oils, which are then collected by condensation. It is the most widely used method.
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Solvent extraction: uses organic solvents (such as hexane) to obtain concentrated extracts known as absolutes, especially used in the perfumery industry.
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Cold pressing: mainly used for citrus fruits, this method applies mechanical pressure to the peel to release the essential oils.
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Supercritical CO? extraction: an advanced technology that uses carbon dioxide in its supercritical state as a solvent, enabling clean, efficient and selective extraction.
Equipment and key differences between the enfleurage method and supercritical CO? extraction
The enfleurage method and supercritical CO? extraction represent two ends of the technological spectrum in essential oil extraction: the former is manual and largely obsolete, while the latter is automated, clean and highly controlled.
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Equipment: The enfleurage method requires simple toolsglass chassis, vegetable fat and manual handling instruments. In contrast, CO? extraction uses stainless steel autoclaves, pressure and temperature control systems, CO? pumps, separators, and sometimes fractionation units.
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Operating conditions: Enfleurage is carried out without heat or pressure but requires extended periods. CO? extraction operates under supercritical conditions (above 73 atm and 31?°C), allowing for fast, precise processes.
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Efficiency and scalability: The enfleurage method has limited scalability and is only suitable for fragile flowers. Supercritical CO? technology enables the efficient processing of a wide variety of plant matrices on an industrial scale.
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Sustainability and safety: CO? extraction avoids the use of toxic solvents, leaves no residues, and produces safer, more sustainable final products.
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