Antioxidant profile of Stevia rebaudiana Bertoni cultivated in Portugal and submitted to different conservation conditions
Artigo de Conferência
Visão geral
Visão geral
resumo
The demand for natural sweeteners has been gaining more and more importance due to the great controversy
associated with the use of some synthetic sweeteners as cyclamates, aspartame and acesulfame-K. The steviol
glycosides (E 960) are a group of natural sweeteners of generalized use; these compounds are obtained from
Stevia rebaudiana Bertoni, a sweet plant native from South America (Carocho et al., 2015). However, Stevia
rebaudiana Bertoni may have other uses to be exploited, in particular due to its antioxidant capacity. This plant
is already produced in Portugal but it is important to evaluate if the plant chemical composition is maintained
regardless of culture conditions. Therefore, in this study, stevia samples were cultivated in Braganca (northeastern
of Portugal) in a field trial with defined culture conditions. After harvesting, the plants were submitted
to two different treatments: kept fresh by freezing (-20°C) and oven-dried (30°C). The antioxidant profile of
the samples was studied through evaluation of free radicals scavenging activity, reducing power, phenolic
compounds (HPLC-DAD-ESI/MS), tocopherols (HPLC-fluorescence) and free sugars (HPLC-RI). Significant
differences were observed: while oven-dried samples showed the highest antioxidant activity and phenolic
compounds concentration (mainly 5-O-caffeoylquinic acid and 3,5-O-dicaffeoylquinic acid), the frozen fresh
samples had the highest values of total tocopherols and total sugars. These results confirm that the plants grown
in Bragança have excellent bioactive secondary metabolites responsible for the observed antioxidant capacity.
