In experiments featured in a Global Stevia Institute-financed study, all nine approved steviol glycosides were detected in all untreated stevia sample leaf preparations.
The team said that distribution patterns of the analysed steviol glycosides mirrored those found in different stages of the commercial-scale extraction and purification process.
The results, made by the team from Bonn University in Germany, add to previous findings that also point to the plant’s robust properties.
Previous investigations of two of the glycosides, stevioside and rebaudioside A, demonstrated their stablity in pH ranges of two to ten and their lack of chemical change after heat treatments.
This stability during food processing joins a list of other benefits exhibited by these glycosides, which include their extreme sweetness (200–350 times sweeter than sugar) and phenylalanine-free status.
Despite this, rebaudioside A’s drawbacks is its bitter taste, making rebaudioside D and M more attractive to food makers.
The cost of commercialising them has also been a major drawback in their uptake due to the relatively low amounts that naturally occur in the leaf.
Suppliers of the study samples of stevia, PureCircle have recently been in the limelight with news of its stevia plant that has 20 times more sweet-tasting steviol glycoside content than standard stevia.
Plans to cultivate the StarLeaf plant to commercial levels have already begun with harvesting expected to begin in August this year.
The Malaysian-based producer said the non-GMO, leaf-extracted sweetener would be available for food and beverage manufacturers to purchase.
Three different production batches containing either the dried stevia leaves (SL), the first aqueous infusion of the ground stevia leaves (ESL) and the high-purity stevia leaf extract samples (with more than or equal to 95% steviol glycosides (SLE95), were prepared.
These were then analysed using high-performance liquid chromatography, ultra-violet (HPLC-UV) and and high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) – two powerful techniques that are able to separate, identify, and quantify each component in a mixture.
The results indicated that the commercial powders of extracted steviol glycosides with an estimated purity of more than or equal to 95% contain the same steviol glycosides as the dried stevia leaves and their hot water infusions.
“In comparison with the US Pharmacopeia steviol glycoside reference standard, the analysis of SLE95, ESL and SL samples confirmed the presence of the nine steviol glycosides (Stevioside, Rebaudioside A, Rebaudioside B, Rebaudioside C, Rebaudioside D, Rebaudioside F, Dulcoside A, Rubusoside β, Steviolbioside) in each of the examined stages of the extraction and purification process,” the study reported.
The team also found that the minor steviol glycosides, currently unauthorised by most regulatory authorities, showed minor changes, which were deemed worthy of further examination.
“The slight variation in rubusoside, rebaudioside B and steviolbioside contents may have been due to differences in the efficiency of extraction and/or analytical measurements.”
Steviol glycoside’s safety profile has been confirmed by the European Food Safety Authority (EFSA) in 2010, which also adopted the Joint Expert Committee on Food Additives’ (JECFA) acceptable daily intake (ADI) of four milligrams per kilogram body weight per day (mg kg bw per day) set in 2009.
While EFSA is currently evaluating the approval of 40 or so steviol glycoside types, 11 of these contained in high-purity stevia leaf extracts, have found uses as a potent sweetening food additive.
Its adoption in drinks such as Coca-Cola Life and Pepsi True has propelled stevia further into the limelight although Coca-Cola recently announced its product was to be withdrawn from UK markets from June.
Source: International Journal of Food Science & Technology (IJFST)
Published online ahead of print: DOI: 10.1111/ijfs.13494
“Steviol glycosides are not altered during commercial extraction and purification processes.”
Authors: Anne Oehme, Matthias Wüst, Ursula Wölwer-Rieck