Stevia: Natural Sweetener
Extraction of Steviol Glycosides
High-purity stevia is extracted and purified from stevia leaves in a manner that is similar to that of sucrose from sugar cane. Specific variables involved in the extraction and purification of steviol glycosides may vary among producers, but for all the processes applied, the process starts with the leaves of the S. rebaudiana Bertoni plant, which are dried and crushed. They are then steeped in warm water.
Steviol glycosides are soluble in water and can be extracted in large-scale commercial processes. This water extract is dark brown because of other constituents in the leaves, such as fiber, dyes, polyphenols, and salts, which are also extracted during extraction process.
Purification steps remove the non-sugar components, and the remaining steviol glycosides are spray-dried to an off-white intermediate that contains between 80 and 95% steviol glycosides. This end product is further purified by crystallization using water or ethanol mixtures to a white end product with a purity of ≥95%. These purification steps are physical processes used to remove unwanted constituents of the leaves, which enable steviol glycosides to be concentrated.
Is Stevia Sweetener Natural?
Some have called into question this conclusion and therefore the naturality of high-purity stevia leaf extract. To address this question, a recent study determined whether steviol glycoside molecules are altered or if their pattern is changed during the process of extraction and purification from the leaves of the stevia plant to the high-purity end product. Three separate batches of a large-scale commercial extraction and purification process, which included the dried leaves, the first water extract, and the final product, a stevia leaf extract with a purity of >95% (SLE95), were examined.
The results have confirmed that steviol glycosides tested in this study were not chemically modified or degraded during the traditional large-scale commercial extraction and purification processes used to produce high-purity steviol glycoside sweeteners, thus providing support for the natural authenticity of steviol glycosides.
Samuel, Priscilla, et al. “Stevia leaf to stevia sweetener: exploring its science, benefits, and future potential.” The Journal of nutrition 148.7 (2018): 1186S-1205S.
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