Comparatively Speaking: Solubility vs. Extraction

By: Anthony J. O'Lenick Jr., Siltech LLC

Posted: April 24, 2012

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Over the centuries, a variety of techniques have been employed to extract active ingredients from botanicals. Solvent-based extraction is one such methodology. After segregating the plant material into its constituent parts, e.g., leaves, stems, fruits, branches and roots, the part with the desired active(s) is chosen, macerated (or similarly processed) and placed into the solvent. Materials that are soluble in the solvent are dissolved, leaving insoluble materials behind.

Solvent-based extraction systems are recognized as having at least two important limitations. First, they are able to extract only active materials that are soluble in the chosen solvent. Second, because many solvents lack selectivity, compounds other than those that are desired are extracted. Not only can this dilute the purity of the desired active compound, it can also negatively impact the performance benefits of the extract.

A number of techniques have been used for extracting water-soluble actives. For example, hot water extraction removes water-soluble materials, leaving behind oil-soluble materials as well as materials that are insoluble in either water or oil. Tinctures, produced using hydro-alcoholic solutions, are another extraction vehicle well-known to skilled artisans. The inclusion of alcohol alters the polarity of water, producing different and marginally more efficient (e.g., higher-yielding) extracts than water or alcohol alone. Propylene glycol is yet another commonly used vehicle to extract water- and alcohol-soluble materials.

The solvent used to extract actives is referred to as menstruum. The menstruum is chosen so that the maximum concentration of active is removed from the matrix while also minimizing the undesired materials extracted. This optimization of extraction is key to the extraction business. New silicone based menstrua have been applied to the extraction process providing some improved performance.¹

Silicone Polymer Extractions