Botanical Ingredients: Extraction Methods

March 30, 2011

A look at the positives and negatives of conventional solvents and organic non-chemical solvents.

Safety concern is growing over the conventional use of chemical solvents, like hexane, in consumer foods and supplements. These solvents, while intended to be removed down to negligible levels, are gaining an increasingly “toxic” reputation.

At the same time, consumer demand for products completely free of chemical solvents is increasing, and some manufacturers are answering the call with options for nonchemical extraction methods. Leading dietary supplement manufacturers like New Chapter (Brattleboro, VT) and Gaia Herbs (Brevard, NC) have already promised to only sell products made solely through organic extraction.

“As consumers are becoming increasingly aware of carcinogenic processing aids (such as bisphenol-A in plastic food containers), they are also inquiring about how their dietary supplements are made” says Graham Rigby, vice president of science and innovation at New Chapter. “Many consumers are surprised to learn many herbs and supplements are extracted using the same chemicals employed in dry cleaning (hexane) and nail-polish remover (acetone).”

Where water and ethanol may not be sufficient, high-tech, eco-friendly extraction methods have emerged. An increasingly hot commodity is supercritical carbon dioxide (scCO2) extraction. “This technology has emerged as a superior alternative to the conventional techniques for extraction of natural products in the food and herbal industries,” says Shaheen Majeed, marketing director for Sabinsa Corp. (East Windsor, NJ), which produces botanical ingredients from chemical and nonchemical solvent derivatives. “ScCO2 is a simple extraction process that uses a dense gas (carbon dioxide) as a solvent for extraction, above its critical temperature and critical pressure.”

The environmental benefits of scCO2 are many. CO2 is used, but is not given off. The final product is free from residual solvent, and this whole process holds Generally Recognized as Safe (GRAS) status.

However, “CO2 extraction cannot replace hexane extraction for products like bulk vegetable oils such as soybean oil,” says Karl-Werner Quirin, PhD, managing director for Flavex Naturextrakte GmbH (Rehlingen-Siersburg, Germany), a global leader in CO2 extraction. “Despite safety, environmental, and health concerns, here supercritical extraction is no alternative, for technical as well as economical reasons.”

For now, conventional chemical solvents still have a place in industry-the equipment is less complex, extraction methods are simpler, and some ingredient sources rely on conventional chemical solvents as the only current means for extraction. Regulatory groups throughout the world also set safety levels for minimum residuals of these solvents in the finished product.

Mark Blumenthal, founder and executive director of the American Botanical Council (ABC; Austin, TX), points out that chemical solvents often have links to the very grounding of health claims for botanical extracts. Blumenthal coauthored a forthcoming ABC white paper on solvents used in herbal extracts and natural food ingredients.

“A lot of the claims structure for this industry is dependent upon research in which herbal extracts using conventional solvents were used,” he says. “Those solvents presumably met the appropriate levels regarding allowed residual levels.”

Still, for those looking for other options, manufacturers can seek out ingredient suppliers that are looking to avoid use of chemical solvents.

Sabinsa uses a state-of-the-art continuous extractor to mitigate solvent risks in large-scale extraction. The company says that closed-system solvent recovery allows for more-exhaustive use of needed solvents, while reducing tenfold the amount of solvents that enter the outside environment.

Other companies throughout the world are taking extra steps to reduce conventional chemical solvent exposure as much as possible.