Stevia was first developed for commercial use in Japan in the 1970s, and China is now the world’s largest producer.
But despite its extensive use over the last 35 years, researchers writing in Food Chemistry pointed out that stevia studies were usually exclusively focused on the determination of steviol and its glycosides, with relatively little research in other areas.
“The extensive knowledge achieved so far about some steviol glycosides contrasts with the lack of information about the composition of other families in stevia. Few stevia researchers have focused their attention on other families different from steviol glycosides,” they wrote, before referring to a small number of studies that had assessed the phenol composition of stevia leaves and the free amino acids in extracts.
“The overall profile has not been evaluated yet,” they added.
“Thus, the main objective of this study was to characterize stevia leaves by analysis of extracts obtained with polar and non-polar solvents in order to increase the detection coverage.”
Comprehensive profiling of the compounds present in stevia leaves was achieved using an LC–QTOF MS/MS-based method.
The researchers said they “tentatively identified” 89 compounds in the polar and non-polar extracts of the plant, and classified into different families.
“Steviol glycosides, and quinic and caffeic acids and derivatives, resulted to be the two families of compounds that characterized the polar extracts of stevia,” they said.
In addition to the more widely documented phenolic compounds, the research team also identified some lesser-known compounds.
Arguably of most interest was the identification of a number of oligosaccharides, one of which has been found to have anti-obesity properties.
“Four compounds were tentatively identified within this group in both ionization modes generating the [M−H]− or the [M+H]+ adduct. A particular case is gamma-cyclodextrin, a ring formed by 8 glucoses that generated the [M+3H]3+. This compound is considered as soluble fiber and to which fat blocker and anti-obesity properties have been attributed,” they noted.
The researchers recommended further investigation into these lesser-known properties to see what additional commercial benefits they could bring.
“This study reveals the wide range of interesting compounds that are present in stevia and that endow the extracts with beneficial properties, in addition to the sweetening power of steviol glycosides. These results can lead to further studies of the families here identified to provide benefits to commercial products from stevia,” they concluded.
Source: Food Chemistry
Published online ahead of print. http://dx.doi.org/10.1016/j.foodchem.2016.09.148
“Characterization of Stevia leaves by LC–QTOF MS/MS analysis of polar and non-polar extracts.”
Authors: M. Molina-Calle, et al.