Key Processes & Know-How for Botanical Extractions

Justin Klinger, Nov 19, 2020 6:45:00 AM

botanical extraction

Since ancient times, civilizations around the world have recognized useful characteristics of various flowers, bark, stems, leaves, roots, and resins, and have incorporated them into medicinal, cosmetic, and culinary practices. 

Extraction describes a process of liquid/solid separation. In a nutshell, that means adding a liquid to solid raw material, then separating the solids from the solution.

Over time, extraction methods have become more sophisticated, from soaking or fermenting plants in water to liquid CO2 extraction and beyond.

Interest in herbal and botanical products has increased in recent decades, as consumers’ interest in improving their health grows.

For products that consumers ingest, inhale, or apply to the skin, toll processors work to optimize processing methods to draw out more of the desired compounds while reducing or eliminating unwanted components.

Here, we’ll take a look at some extracted products, extraction methods used in toll processing, and a few important processes and analyses for botanical and herbal extractions.

Essential Oils, Extracts, and Absolutes

Essential oils are concentrated volatile oils — meaning they evaporate quickly in air — derived from plant material. Most essential oils are lighter than water, with a few exceptions like cinnamon and bitter almond. This weight difference facilitates their separation after extracting.

A large volume of plant material is needed to produce essential oils, and their makeup can be complex, with hundreds of volatile components such as alcohols, esters, ethers, hydrocarbons, aldehydes, and more.

Some essential oils have long been used for fragrance, flavor, and medicinal purposes. Others may be used as antibacterial agents or insect repellent ingredients.

Besides essential oils, extracts and absolutes are also products of extraction. Absolutes are the result of a more complex process using chemical solvents and evaporating or distilling to remove the solvent. 

Extracts, on the other hand, are made up of phytochemicals left in a solvent (water, glycerin, and alcohol are common). Tinctures, which use alcohol as a solvent, are common extracts. Vanilla extract is a common example.

The different products have different uses, and many considerations go into selecting the most appropriate processing methods.


Water distillation may be one of the oldest extraction methods. Plant material is basically boiled in water, releasing essential oils in the steam. When the steam is condensed, plant oils and water separate. Water distillation is simple, but it is often an incomplete method, and for some plants, long exposure to high heat can affect the quality of the product.

Steam distillation is a commonly used method, especially for more heat-sensitive herbs and botanicals such as lavender or other flowers. Steam quickly vaporizes volatile compounds, and the vapor is condensed, allowing the two fractions (water and extracted compounds) to separate.

Fractional distillation takes this concept a step further, heating steam to specific, different temperatures at which each desired component vaporizes. This process fractionates the different chemical compounds in a plant, collecting them in separate batches. Camphor and ylang-ylang are commonly known products of fractional distillation.

This method is also used to redistill oils to remove unwanted or toxic components. Almond oil, for example, is fractionally redistilled — or rectified — to remove naturally occurring hydrocyanic acid. 

Finally, some hydrosols, or aromatic waters like rosewater and orange flower water, are valuable by-products of the distillation process.

Solvent Extraction

While water is technically a solvent, other solvents are often used for herbal and botanical extraction. Commonly used solvents can include methanol, ethanol, hexane, and petroleum ether. A solvent is selected for suitability with the desired solute, and is added to plant material that has been finely milled to optimize penetration and extraction.

Solvent processing requires scientific expertise and technical process control, from the material fineness to solvent selection to time and temperature controls. It’s a useful method for more delicate plant materials whose essences aren’t readily extracted by steam.

Some solvents can leave a residue, and residue levels are strictly regulated. Lab analysis capabilities such as gas chromatography-mass spectrometry are crucial for determining the composition and quality of the final product.

Supercritical Carbon Dioxide

Pressurized carbon dioxide can shorten extraction time and eliminate solvent residue concerns in the final product. Under pressure, CO2 reaches a supercritical state, with a density of liquid. In this state, it acts like a liquid solvent to extract essential compounds from plant material more completely than steam.

Unlike many other solvents, CO2 is nontoxic and nonflammable, and leaves no residue. Because it uses relatively low temperatures, this method is less likely to degrade flavors, colors, or essences, for a clean, unadulterated, high-quality end product.

By controlling pressures and flow rates, expert extractors can target compounds for extraction and leave behind unwanted contaminants. As pressure is relieved, the CO2 dissipates, leaving a high-quality extract composed of low molecular weight compounds such ethers, esters, terpene, hydrocarbons, ketones, and alcohols.

CO2 extraction is a sought-after toll processing capability for hemp product manufacturers, and it is also a preferred method for herbs including melissa, rosemary, and kava kava, among others. While solvent extraction is sometimes used for these products, supercritical carbon dioxide reduces the need for further refinements. This, in addition to shorter processing time, can mean much faster speed to shelf.

Important Analyses, Process Knowledge, and Services

While it’s important to know your toll processor has the capabilities you need, your investigation shouldn’t start and end there. 

Your extraction process may require crucial pre-process steps, from fine milling to meet a particle size specification, to decarboxylation for specialty CBD extracts. Your trusted toll processor should be able to provide analytical lab services, QC, and quality assurance processes for cGMP and FSSC 22000, as well as organic, kosher, and halal certifications.

You may also need to consider packaging, labeling, and logistics to help eliminate supply chain bottlenecks and improve your speed to market. You can save time, cost, and efficiency by entrusting your extraction projects to a single, start-to-finish toll processing expert with teams capable of handling every step, and advising you on process improvements and optimizations along the way.

Learn about these processes, equipment, analyses, certifications, and more with our Particle Technology Glossary. Click the link below to download your copy. After you’ve had a chance to read it through, we’ll be happy to answer any questions you have. Just contact us.New call-to-action

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