Used for their cosmetic and therapeutic properties, phytosterols are compounds derived from certain plants and seeds. What are the main plant sources of phytosterols? And how are these extracted? Let's discover this together.
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How are phytosterols obtained?
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Published July 6, 2023,
updated on January 29, 2024,
by
Pauline, Chemical Engineer
—
4 min read
Phytosterols: What are their benefits?
Naturally occurring in plants, phytosterols belong to the sterol family. Their structure and function is comparable to that of human body cholesterol . The consumption of phytosterols has beneficial effects on health, particularly on cardiovascular health. Indeed, they are capable of reducing cholesterol absorption in the intestine, which contributes to lowering cholesterol levels in the blood.
Phytosterols are also recognised for their cosmetic properties and their benefits for the skin and hair. These compounds, suitable for sensitive skin, are notably anti-inflammatory and soothing. Phytosterols are also good humectant agents. Moreover, they possess antioxidant properties. These come from their cyclic chemical structure which allows them to stabilise free radicals by donating an electron before they can damage DNA and cellular constituents. Finally, a recent study demonstrated that phytosterols could delay skin ageing. They act by inhibiting collagenase, the enzyme that breaks down the peptide bonds of collagen. The loss of structure of this compound results in its loss of function and a decrease in skin elasticity.
How are phytosterols extracted?
The phytosterols are found in a wide variety of plants. They are obtained by purifying the oil extracted from these plants. Among the main sources of phytosterols, we find soybean oil, corn oil, avocado oil, pine bark extract, certain whole grains and some berries. Here are the different steps followed when phytosterols are extracted from pine bark:
Bark Collection : The bark is sustainably harvested in a way that preserves the trees and the surrounding ecosystem. This collection is done when the outside temperature is moderate and the tree's moisture content is relatively low, which generally corresponds to mid-spring or early autumn. The bark is then dried to facilitate the upcoming extraction process.
Grinding : the dried bark is ground into a fine powder to increase the contact surface and facilitate the extraction of active compounds.
Extraction : Various extraction methods can be employed, such as hot extraction or pressure extraction. Hot extraction is a process that involves boiling pine bark in water for several hours. This allows the active ingredients of the pine bark to be released. Pressure extraction, on the other hand, relies on the application of pressure to the pine bark powder, typically using a hydraulic piston, to extract the oils and active compounds.
Collection : The extract, obtained in liquid form, is collected from the output of the extraction device. It is then filtered to remove any residual solid particles and purified.
Crystallisation and Purification : To extract the phytosterols from the oil, a crystallisation process is carried out. The solution is cooled to form phytosterol crystals, which are then purified through filtration and successive washes, to remove any remaining traces of oil.
Drying : once purified, the phytosterols are dried using a desiccator, creating a partial vacuum, to eliminate any residual moisture.
Sources
CABRAL J. & al. Phytosterols: applications and recovery methods. Bioresource technology (2007).
BECKER L. Safety Assessment of Phytosterols as Used in Cosmetics. Cosmetic ingredient review (2013).
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