| Rebaudi,
a chemist, was the first to study the sweetening substance
of the Stevia although he classified it erroneously as Glicirricina.
In
further studies, that have included sensory tests, it has
been found that the Rebaudioside A has the best flavour
besides being the closest to that of sugar. A slightly bitter
flavour can be detected in the sweetness of the Steviosido
and Rebaudioside A. It is a peculiarity that exists in minute
quantities, and is due to having in their composition traces
of Alfa-rhamosyl instead of Beta-glucose.
Commercial companies in many countries have been studying
each of these components, through physical and chemical
means, in order to eliminate the slight bitter flavour in
the sweetness. Besides, genetic investigations must be pursued
by which it may become possible to select the plants that
will eventually not contain rhamosyl, which causes the slight
bitter taste. In 1999 the Steviafarma S.A. company of Maringa-Brazil
managed to eliminate, after six years of investigations
and through the use of chemical solvents, the bitter taste
and thereby obtaining 98% of Steviosida, Rebaudiosida A
as well as other rebaudiosides with 250 and at times 300
higher content of sweetness than that of saccharine, actually
authorised by the FDA of the United Sets and commercialised
in various countries of the world.
Schock
(1982) (4). Has expressed that the interesting chemical
components are the Steviosido, Rebaudioside A; besides,
there exist at least six sweet components united to a central
structure of three carbon rings, whose chemical structure
is so described.
According
to this investigator the concentrations of Stevioside reaches
between 3 and 10% of the weight in dry leaf matter, the
Rebaudioside A, less concentrated, varies between 1 and
35%.
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