The Botanical Origin of Stevia
Stevia's story begins with the Stevia rebaudiana shrub, native to South America. The indigenous Guarani people have historically used its leaves, known as ka'a he'ê or "sweet herb," for sweetening and medicinal purposes. The sweetness comes from naturally occurring steviol glycosides in the leaves.
The Refined Extraction Process in the U.S.
In the U.S., the FDA has not approved the whole stevia leaf or crude extracts for food use. Instead, U.S. products use highly purified steviol glycosides, primarily rebaudioside A (Reb A). The commercial process is similar to brewing tea but on a larger scale. It involves harvesting and drying stevia leaves, which are now cultivated in the U.S. and other countries. The dried leaves are steeped in hot water to extract the steviol glycosides. The resulting liquid is filtered and purified to isolate the sweet compounds. Finally, crystallization concentrates the solution to achieve a high-purity extract with at least 95% steviol glycosides, which is approved by the FDA as a sweetener.
Modern Production Methods in the United States
Beyond traditional extraction, modern techniques are used to create specific steviol glycosides with improved taste, such as rebaudioside M (Reb M), which has less bitterness and is less abundant naturally.
Comparison of stevia production methods
| Method | Starting Material | Process | Benefits | Drawbacks |
|---|---|---|---|---|
| Extraction | Stevia leaves | Steeping leaves in water, filtering, and purifying. | Considered the most traditional; yields highly purified Reb A. | Can result in bitter aftertaste from other glycosides. |
| Bioconversion | Extracted steviol glycosides | Using enzymes to convert one glycoside (e.g., Reb A) to a more desirable one (e.g., Reb M). | Enables large-scale production of better-tasting glycosides. | Enzymes often from genetically modified micro-organisms. |
| Fermentation | Genetically modified micro-organisms | Micro-organisms engineered to produce steviol glycosides from sugars. | Highly scalable and cost-effective; produces specific glycosides. | Uses genetically engineered organisms, which some consumers prefer to avoid. |
Commercial sweetener brands frequently combine these refined steviol glycosides with other ingredients, like erythritol or dextrose, to enhance flavor and texture.
Regulatory Status in the U.S.
The U.S. regulatory landscape is key to what stevia products are available. The FDA granted Generally Recognized As Safe (GRAS) status to high-purity steviol glycosides in December 2008, allowing their use as food additives. The FDA maintains that whole stevia leaf and crude extracts are not approved for food additives due to insufficient safety data.
U.S. Cultivation and Production
While stevia is native to South America, cultivation is expanding globally, including in the U.S., particularly in the southeast. U.S. growers are entering the market to meet domestic demand and ensure a consistent supply. For instance, Splenda operates a large stevia farm in Florida. Growing stevia domestically allows for greater control over the process, from farming to quality, potentially reducing transport costs and environmental impact.
Conclusion
In the United States, commercial stevia is derived from the Stevia rebaudiana plant but is a highly refined extract of its sweet steviol glycosides, not the whole leaf. The production involves extraction and purification, similar to brewing tea, to concentrate the sweetness and remove bitter compounds. Alongside traditional methods, bioconversion and fermentation are used to produce specific, better-tasting glycosides like Reb M. This purified extract has FDA GRAS approval, unlike the crude leaf. Growing domestic cultivation and advanced processing ensure a high-quality, zero-calorie sweetener is available to U.S. consumers. The International Stevia Council offers further information on production technologies and global standards.
